69 chapter four THE DIGESTIVE SYSTEM THE DIGESTIVE DIGESTIVE THE SYSTEM The digestive system is structurally divided into two main parts: a long, winding tube that carries food through its length, and a series of supportive organs outside of the tube. The long tube is called the gastrointestinal (GI) tract. The GI tract extends from the mouth to the , and consists of the mouth, or oral cavity, the , the , the , the , and the large intes- tine. It is here that the functions of mechanical , chemical digestion, of nutrients and water, and release of waste material take place. The supportive organs that lie outside the GI tract are known as accessory organs, and include the teeth, salivary , , , and . Because most organs of the digestive system lie within body cavities, you will perform a dissection procedure that exposes the cavities before you begin identifying individual organs. You will also observe the cavities and their associated membranes before proceeding with your study of the digestive system.

Exposing the body cavities should feel like the wall of a stretched balloon. With your skinned cat on its dorsal side, examine the cutting lines shown in Figure 4.1 and plan 2. Extend the cut laterally in both direc- out your dissection. Note that the numbers tions, roughly 4 inches, still working with indicate the sequence of the cutting procedure. your scissors. Cut in a curved pattern as Palpate the long, bony and the softer, shown in Figure 4.1, which follows the cartilaginous xiphoid process to find the ventral contour of the diaphragm. Make your midline. Then, follow these instructions: cut through all muscle layers and con- nective tissue, but be careful to avoid 1. Begin your #1 incision by inserting the cutting too deeply and damaging the point of your scissors through the muscle underlying organs. Find the diaphragm 1 layers about ⁄4-inch caudal to the tip of again, and withwww.eig.net a scalpel, carefully cut it the xiphoid process. Make the cut large from its attachmentsFigure 6.6 to the ventral body OUTERNET Publishing enough for your finger to poke through, wall. Allow the diaphragm to remain on then insert your finger into the body cav- top of the liver. ity to feel the space beneath the muscle layers. Your incision was very likely made 3. From your first incision, use your scis- just caudal to the diaphragm, an internal sors to cut in a longitudinal direction 1 muscular partition dividing the thoracic roughly ⁄4-inch to one side of the ventral and abdominopelvic cavities. Press your midline. While cutting, pull upward finger gently against the diaphragm; it (toward you) with the scissors to create 70 Chapter Four

Midventral line

5

5

1

Diaphragm

2 2

3

4

4 4 4 4 © bluedoor, LLC

Figure 4.1 – Cutting guide for exposing body cavities (the numbers correspond to the sequences in the text).

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Figure 4.1 OUTERNET Publishing THE DIGESTIVE

SYSTEM © bluedoor, LLC bluedoor, © 71 Parietal pleura pleura Visceral Parietal pericardium Visceral Diaphragm Parietal Ventral body cavities. – Figure 4.2 Figure OUTERNET Publishing www.eig.net Figure 4.2 cavity Pericardial The Digestive System 72 Chapter Four

a space between the body wall and the Thoracic Cavity visceral organs. If performed carefully, The thoracic cavity is the potential space located this technique will help prevent the scis- cranial to the diaphragm. It is lined by a moist sors from cutting into the organs. membrane called the parietal pleura. The pari- etal pleura continues inward to cover both , 4. Extend your cut down one side of the forming the visceral pleura. Between the two ventral midline caudally at first, but pleural membranes is a moist space called the stop when you feel the resistance of a pleural cavity. The thoracic cavity also includes membrane near the . the pericardial cavity along its midline, which 1 Then cut laterally about ⁄2 inch, then contains the . The pericardial cavity is sand- 1 caudally another ⁄2 inch, then continue wiched between two layers of the pericardium, the horizontal cut to the iliac crest which includes an outer parietal pericardium (see Figure 4.1). These cuts will enable (or pericardial sac) and an inner visceral pericar- you to cut around the genital region dium. In addition, the potential space located without damaging it. cranial to the heart is known as the mediastinum, which contains the major vessels of the heart and 5. Now you are ready to expose the thoracic the . cavity. Extend your midventral incision toward the neck region from the #1 inci- Abdominopelvic Cavity sion near the xiphoid process, and cut The abdominopelvic cavity is the large cavity in a cranial direction. As you reach the located caudal to the diaphragm. It is lined by neck region, you will have to proceed a membrane attached to the inner body wall very slowly to avoid damaging the arter- called the parietal peritoneum. The parietal ies (colored red with latex), (col- peritoneum extends inward to wrap around ored blue with latex), and (white). many of the organs of the abdominoplevic cav- Cut only to expose the ity. The part of the peritoneum covering most organs lying deep in the neck, including of the visceral organs is known as the visceral the , gland, and . peritoneum. The cavity between the two peri- toneal membranes is called the , 6. With your cutting complete, reflect the and contains a small amount of fluid that helps thoracic and abdominal walls to reveal reduce friction between adjacent visceral organs. the internal cavities. You will have to The peritoneum also includes numerous exten- fracture to reflect the , sions, or folds, which will be described later in so press the walls laterally until you hear this chapter. The abdominopelvic cavity contains the snapping sound. Since the fractured many visceral organs, including the stomach, ends of the ribs can be sharp, take care to small intestine, , liver, pancreas, avoid cutting yourself. gallbladder, internal reproductive organs, and more. Its larger cranial portion is the abdominal Ventral Body Cavities and cavity, which extends from the diaphragm to the level of the iliac crest. The smaller caudal area is Membranes the bowl-shaped pelvic cavity. Now that you’ve exposed the ventral body cavi- ties and their associated membranes, identify Cranial Digestive Structures them from the descriptions that follow (Figure 4.2). The ventral is also known as the The organs and associated structures of the diges- , or coelomic cavity. tive system will be described sequentially from the salivary glands around the mouth to the anus. The system has been divided into a cranial por- THE DIGESTIVE SYSTEM

- - - - 73 LLC bluedoor, © parotid duct, which crosses over Sublingual gland face is the the masseter muscle before entering the ves tibule (space between the teeth and the ). premolar upper third the to opposite opens It tooth. located immediately ventral to the gland parotid and posterior to the angle of the man- dible (Figure 4.3). The duct emerges from the anterior edge of each gland, then extends laterally beneath the digastric muscle to enter the floor of the oral cavity just anterior to the lingual frenulum (beneath the ). located at the anterior end of each mandibu paral extends duct sublingual The gland. lar lel to the submandibular duct, although it is smaller and difficult to observe. vary glands, theylocated superficial are to the paired on masseter each side of muscle structuresthe head just below the (Figure 4.3). Emerging from its rostral sur MANDIBULAR GLANDS: paired glands, each SUBLINGUAL GLANDS: small, paired glands PAROTID GLANDS: the largest of the - sali

- Figure 4.3 Figure OUTERNET Publishing www.eig.net www.eig.net Salivary glands (lateral view of the head and neck). – Masseter Parotid duct Parotid Figure 4.3 Parotid gland Parotid salivary glands, carefully remove Mandibular gland The salivary glands are located in the head The Digestive System region surrounding the oral cavity. They are soft, soft, are They cavity. oral the surrounding region lobular structures that connect to the oral cavity by way of a duct. Salivary glands glands are exocrine that secrete a watery ducts that carry it fluid, into the oral cavity when food saliva, into glands salivary major three has cat The present. is and two minor glands.

Salivary Glands To expose the tion and a caudal portion, with the diaphragm serving as the line of division between the two. The cranial digestive structures include the sali any and fat that remains on the the on especially neck, and head the of side lateral to careful very Be muscle. masseter the of surface avoid damaging vessels, nerves, and small tubes that you see as you clean. vary glands, oral cavity, pharynx, and esophagus. Locate each structure in your cat and identify its characteristic features. 74 Chapter Four

MOLAR GLANDS: a minor pair of salivary the jaw on one side of your cat. Using glands in the cat, each located at the angle shears, cut the condyloid portion of the of the jaw immediately deep to the (not on the same side. Pry the mouth open, and shown). Several small, inconspicuous ducts locate the following structures of the oral cavity open at the inner surface of the cheeks. (Figure 4.4). ZYGOMATIC GLANDS: a minor pair of sali- vary glands, each located in the floor of the VESTIBULE: the part of the oral cavity located (not shown). A small duct from between the teeth and cheeks. Notice the each gland opens at the posterolateral part of labial frenulum, which is a fold of tissue the roof of the mouth. through the midline of the vestibule connect- The salivary glands of include the large ing the upper and lower . parotid glands, the submandibular glands, and the TEETH: the dental formula for the cat is as fol- sublingual glands. The parotids are located similarly lows: for the upper jaw, 6 incisors, 2 canines, to those of the cat, and the parotid duct opens into 3 premolars, and 2 molars (6:2:3:2); for the the vestibule opposite the second maxillary molar lower jaw, 6 incisors, 2 canines, 4 premo- tooth. The submandibulars are paralleled by the lars, and 2 molars (6:2:4:2). This dentition mandibulars in the cat. The sublinguals are located reflects adaptations for a carnivorous diet. anterior to the submandibulars at the base of the The comparative dental formula for adult tongue, and the sublingual duct opens into the floor humans is the same for both jaws: 4 incisors, 2 of the oral cavity directly above the glands. Humans canines, 4 premolars, and 6 molars. Also, the do not have molar and zygomatic glands. canines are shorter and more blunt, and the molars are more flat, which reflect the omni- Oral Cavity vore diet that includes less cutting and ripping, To expose the mouth, or oral cavity, cut through and more grinding. the muscles and connective tissue suspending

Hard palate

Opening to internal Vestibule auditory canal

Oral cavity Tongue Nasopharynx

Lip

Fauces Palatine tonsil Soft palate Oropharynx Epiglottis Laryngopharynx Glottis © bluedoor, LLC Figure 4.4 – Oral cavity and pharynx.

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Figure 4.4 OUTERNET Publishing THE DIGESTIVE SYSTEM - - - 75 internal - audi epiglottis. glottis, which is protected from palatine tonsils, each of which lies canals, which communicate with the peritoneum is the extensive serous mem- esophagus is long, muscular tube that are extensions of the visceral the of extensions are folds peritoneal sible. If one is available, shine a light into the the into light a shine available, is one If sible. nasopharynx the of walls lateral the In cavity. are the openings to the paired tory middle ear. glossal arches and the free caudal margin of the soft palate. The oropharynx communi cates with the oral cavity through the fauces. Embedded within its laterodorsal walls are a pair of partially recessed in a called the tonsilar fossae. shallow depression pharynx. It extends from the oropharynx to the larynx. Its slit-like opening to the larynx is called the passing food particles by known as the a movable fold : OROPHARYNX located between the palato LARYNGOPHARYNX: the caudal part of the bladder, stomach, pancreas, small intestine, and their and organs these observe To intestine. large associated structures, pull back the flaps of abdominal the wall to expose the cavity. abdominopelvic Peritoneum The brane of the abdominopelvic cavity, which you observed when you initially opened the cavity. The Esophagus The transports swallowed material from the pharynx to the stomach. It and travels lies the length of dorsal the thoracic cavity. to At the trachea its caudal end it penetrates unite with the the stomach in the diaphragm abdominal cavity. to Because it is located in the thoracic cavity dorsal to the heart and lungs, the esophagus be dissected will at this not time, but you will be able to observe it during your study of the system (Chapter 5). respiratory Caudal igestive D Structures The structures of the digestion system caudal to located the diaphragm include the liver, gall ------foli- fungiform, the large, filiform, which include . The frenu The frenulum. lingual vallate, and the leaf-shaped The human tongue is very similar, except pharynx is the chamber located caudal to ate. filiform papillae are less abundant and not as sharply pointed, and foliate papillae present. are not both sides of the oral cavity wall, extending from the caudal portion of the soft the palate. They represent tongue the boundary to between the oral cavity and the pharynx. portion of the oral cavity between the palato glossal arches. The fauces oropharynx. leads into the ynx. To view it, make a longitudinal incision longitudinal a make it, view To ynx. care and palate, soft the of midline the along fully pry the two sections apart as far as pos- lary and palatine and . is lined with a muscular partition between the oral cavity and nasal cavity, and is lined with mucous membrane. up the floor of the oral cavity. It is attached to the floor of the mouth by a ventral fold of the called tissue lum can be seen when the tongue from is the lifted floor. The tongue’s tains surface four types of con elevated structures called papillae, which house the taste buds for the reception of taste. In the cat, the most com mon papillae are the of the oral cavity. It is formed by the maxil sharp projections to give the cat surface a for grooming. Other papillae friction include the mushroom-shaped rounded The Digestive System PALATOGLOSSAL ARCHES: lateral folds on FAUCES: the opening at the extreme caudal the fauces, extending from the oral cavity to the larynx (Figure 4.4). It provides a passageway for air traveling to and from the lungs and for food traveling from the mouth to the esophagus. It is commonly divided into nasopharynx, oropharynx, and laryngopharynx. three sections, the NASOPHARYNX: the cranial part of the phar- Pharynx The SOFT PALATE: caudal to the hard palate, it is TONGUE: the large, muscular that makes HARD : PALATE the rostral portion of the roof 76 Chapter Four

Esophagus (abdominal part)

Liver (left medial lobe) Gallbladder Falciform

Common duct Cardia of stomach Liver (caudate lobe) Liver (left lateral lobe)

Fundus of stomach Liver (right medial lobe) Lesser omentum

Liver (right lateral lobe) Body of stomach

Pancreas (cut)

Greater curvature of stomach

Spleen of stomach

Ascending colon

Location of

Cecum

Descending colon

Rectum

Anus Anal gland © bluedoor, LLC

Figure 4.5 – Organs and peritoneum of the abdominopelvic cavity.

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Figure 4.5 OUTERNET Publishing THE DIGESTIVE SYSTEM

- - - 77 LLC bluedoor, © Tail Tail omental bursa, or lesser peritoneal sac, peritoneum that extends from the greater cur greater the from extends that peritoneum vature of the stomach to the dorsal abdomi nal wall. The double-layered sac extending ventrocaudally to the small intestine is called the the pancreas is located within the mesentery proper. neum extending from the lesser curvature of the stomach and the duodenum of the small intestine to the liver. Notice the common bile duct, which is located on the free edge of the lesser omentum. This duct transports bile from the liver and duodenum. gallbladder to the Duodenum Common bile duct Head LESSER LESSER : OMENTUM a double layer of perito GREATER OMENTUM: a double layer of - - Pancreas Pancreas Cystic duct mesentery Figure 4.6 Figure OUTERNET Publishing www.eig.net www.eig.net Gallbladder, biliary ducts, and pancreas. – mesorectum. Note that Figure 4.6 Gall bladder Hepatic ducts mesocolon, and the part attached Opening of the hepatopancreatic ampulla Opening of the accessory duct pancreatic (inconsistent) Main pancreatic duct Main pancreatic proper, the part supporting the large intes extension of the visceral peritoneum of the of wall dorsal the to liver the anchors It liver. the and the diaphragm, and sepa rates the liver into right and left lobes. that extends from the visceral peritoneum of the small and large intestines to the . dorsal The portion that suspends the small intestine is called the tine is the to the is the and parietal peritonea, and include the following (Figure 4.5): FALCIFORM : LIGAMENT a double-layered MESENTERY: a double layer of peritoneum The Digestive System 78 Chapter Four

and contains fat deposits, nodes, and Stomach lymphatic vessels. The stomach is a J-shaped enlargement of the GI tract, located directly beneath the diaphragm Liver on the left side of the abdominal cavity (Figure The liver is the prominent, dark-brown organ 4.5). It functions as a temporary reservoir for lying immediately deep to the diaphragm, with swallowed food, and its inner lining contains most of its bulk on the right side (Figure 4.5). Its that secrete and functions include management of sugar and fat the pepsinogen to begin the process of levels in the blood, storage of toxins, and produc- digestion. The lateral border of the stom- tion of a yellow-green fluid that breaks down fats, ach forms a rounded, convex surface called the called bile. In the cat, the liver is divided into greater curvature, and its medial border forms six lobes. Identify the once a concave angle known as the lesser curvature. again, which divides the liver into right and left Note the peritoneal fold called the greater omen- portions. The left side of the liver includes a left tum, which originates from the greater curvature medial lobe and a left lateral lobe. The right side to hang downward. Also note the flat, elongate, of the liver includes a quadrate lobe adjacent to dark-reddish near the left dorsolateral sur- the falciform ligament, which is partially united face of the greater curvature. The spleen is part with the right medial lobe. Between these two of the . Similar to the human lobes is a depression that contains the greenish stomach, the stomach of the cat is divided into sac known as the gallbladder. Dorsolateral to the following parts: the right medial lobe is the right lateral lobe, and dorsal to it is the smaller caudate lobe. The CARDIA: the part of the stomach that receives human liver is also a prominent organ, but contains the esophagus. It surrounds the lower esoph- only four lobes: a large right lobe separated from the ageal sphincter, the ring of muscle that sepa- smaller left lobe by the falciform ligament, a quad- rates the stomach from the esophagus. rate lobe, and a caudate lobe. FUNDUS: a sac-like, rounded portion that extends laterally to the cardia and slightly Gallbladder craniad. Elevate the right medial lobe and quadrate lobe BODY: the large, central portion of the stomach, of the liver to observe the gallbladder, located which is located caudal to the fundus. in a depression between the two lobes, known as PYLORUS: the narrow, caudal part that the cystic fossa (Figures 4.5 and 4.6). The gall- communicates with the duodenum of the bladder is a thin-walled sac that receives newly small intestine via a sphincter muscle called manufactured bile from the liver for temporary the pyloric valve. storage. When a meal is consumed, the gallblad- der contracts to push bile into the cystic duct. Once you’ve identified the parts of the stomach, The cystic duct combines with numerous hepatic make an incision along the greater curvature from ducts arising from the left lobes and right lateral the fundus to the pylorus, taking great care to lobe of the liver to form the common bile duct. avoid damaging the greater omentum. Notice The common bile duct extends caudally to unite the folds in the wall of the stomach, which are with the duodenum of the small intestine at the called rugae. They allow the organ to expand hepatopancreatic ampulla. Once in the small with incoming food. intestine, bile assists in the digestion of fats. Small Intestine The small intestine is a long, winding tube that extends from the pyloric valve of the stomach to its junction with the large intestine (Figure 4.5). The small intestine finalizes chemical digestion THE DIGESTIVE SYSTEM - - - 79 pan- anus, which is surrounded transverse colon that travels The large intestine of the human , which curves anal glands, open into the rectum hepatopancreatic ampulla. An acces , which ascends from pancreas is a diffuse mass of soft glandular ing from it, known as the , which is lacking in the cat. divided is colon The rectum. the to the into an occupied area the to cecum the with union its by the liver; a transversely from the right side near the liver to the left side of the cranial abdominal cav- ity; and a caudally to descend to the pelvic cavity. intestine. The short rectum opens exterior to via the the by sphincter muscles. A pair of scent glands, known as near the anus. glands Secretions are important from for marking the territorial anal boundaries. is similar to that of the cat, except the human descending the between colon sigmoid a includes colon and rectum, which is an S-shaped curva- ture. Also, humans lack anal glands. : COLON a long, wide segment extending from RECTUM: the terminal segment of the large mones that regulate blood sugar levels, and also in the secretion of digestive and sodium bicarbonate. The digestive enzymes and sodium bicarbonate form the , which is channeled out of the pancreas by the main creatic duct. This duct unites with the common bile duct to be delivered into the duodenum. At the union of the common bile duct and duode num is a small elevation known as the ampulla of Vater, or sory duct may also be present. Pancreas The tissue located within the mesentery the small proper intestine (Figures of 4.5 and 4.6). located It just is below the greater curvature stomach, of and the slightly dorsal to it, and includes a caudal head portion and a cranial tail portion. The pancreas functions in the secretion of hor ------The ileocecal villi, which increase its absorptive nicates with the ileum via the ileocecal valve. It is a short, blind in the right caudal aspect of the abdominal cavity. human cecum includes a fingerlike tube extend tube fingerlike a includes cecum human in diameter, but the shortest extends in from length, the pyloric it valve to its union with the . In the cat, length it ranges from in 12-18 cm (5-7 duodenum inches). receives The the common bile from duct the liver and gallbladder and the pan creatic duct from the pancreas. intestine, it is the longest, with an length of about 50 cm (20 inches) in average the cat. union with the jejunum to the large tine intes about 35 cm (14 inches) in the cat. A doughnut-shaped muscle called the surrounds the junction of the ileum and ileum the of junction the surrounds valve large intestine. Similar to the pyloric valve, it regulates the movement of materials from one organ (the small intestine) to the (the next large intestine), and prevents the reflux of contents in the opposite direction. The Digestive System tine, and prepares and forms the feces. Smooth muscles in the wall of the large intestine contract to move the feces and release it during tion. defeca The large intestine contains the following segments: CECUM: the cranial segment, which commu- Large Intestine The caudal portion of the intestine GI extends from tract, the ileocecal the valve to large the anus (Figure 4.5). It gets its name from larger in diameter along its entire being length than the small intestine, although it is roughly one-third the length. The intes small large the from arrive that contents the from intestine absorbs water and is the only site for nutrient absorption. Its inner lining is characterized by the presence of tiny, fingerlike surface area. Similar to the human small intes tine, the small intestine of the cat is divided into three segments: DUODENUM: the largest of the three segments JEJUNUM: the middle segment of the small ILEUM: the caudal segment, it extends from its

THE DIGESTIVE SYSTEM 81 w Revie ter Chap d. esophagus b. parietal peritoneum d. greater omentum b. pericardial sac d. lesser omentum b. the stomach d. all of the above b. located on the tongue d. do not produce saliva b. liver d. gallbladder b. pancreas d. gallbladder b. duodenum, jejunum, and ileum d. none of the above b. stomach d. pharynx b. peritoneum d. liver b. stomach a. liver c. stomach a. cecum, colon, and rectum c. cardia, body, and pylorus a. duodenum c. cecum a. the abdominal cavity c. the large intestine a. the maxillary glands c. the parotid glands a. pancreas c. duodenum c. small intestine a. pericardium c. parietal pleura a. diaphragm c. falciform ligament a. stomach c. tongue a. liver The Digestive System 10. The first abdominopelvic structure receiving food is the 8. The soft, glandular organ that provides digestive enzymes to the duodenum is the 9. The segments of the large intestine are the 7. The prominent, brown organ beneath the diaphragm on the right side is the 6. The largest of the salivary glands are 4. The structure that separates the thoracic and abdominoplevic cavities is called the 5. The abdominopelvic cavity contains 3. The membrane that lines the thoracic wall is the 2. The digestive organ that is the site of nutrient absorption is the A. Answer the following multiple-choice questions by circling the most correct answer. 1. Which of the following organs forms part of the GI tract? 82 Chapter Four

B. Complete the sentences below by providing the missing terms from the chapter material.

1. The liver, pancreas, and salivary glands are ______of the digestive system.

2. The membrane attached to the inner wall of the abdominopelvic cavity is the ______.

3. The larger, cranial portion of the abdominopelvic cavity is known as the ______.

4. The paired glands located immediately ventral to the parotid gland and posterior to the angle of the mandible are the ______.

5. The rostral portion of the roof of the oral cavity is called the ______.

6. The ______is attached to the floor of the mouth by a ventral fold of tissue called the lingual frenulum.

7. The part of the cat’s throat that contains the palatine tonsils is the ______.

8. A double layer of peritoneum that extends from the visceral peritoneum of the small and large intestines to the dorsal abdominal wall is known as the ______.

9. Bile is channeled into the duodenum from the ______by way of the common bile duct.

10. The union of the small and large intestines is marked by a valve called the ______valve.

C. Answer the following descriptive and critical-thinking questions with a brief explanation in the spaces provided.

1. Describe the process of digestion by including contributions by the oral cavity, salivary glands, stomach, and small intestine.

______

______

______

______

______The Digestive System 83

2. Describe the contributions to the function of digestion by the liver, gallbladder, and pancreas.

______

______

______

______THE DIGESTIVE DIGESTIVE THE ______SYSTEM

______

3. Based on the anatomical similarities between cats and humans, suggest the type of diet that humans are adapted for and explain why.

______

______

______

______

______

______

115 chapter seven THE UROGENITAL SYSTEM

The urogenital system combines two systems, the and the . The two systems are combined in this chapter because of the close anatomical relationship between them, which is common among . As you will soon discover, several urinary organs lie in direct contact with reproductive organs, and in some cases, the functions of both systems take place within a common organ. The overall functions of the two systems are quite distinct, however. The primary function of the urinary system is the formation of , which achieves several roles: the removal of nitrogen-containing materials that result from metabolic activities; the management of the water and salt balance of body fluids; and the regulation of blood pressure. Urine formation occurs in the kidneys, at the site of functional subunits called . Within the nephrons, blood is filtered, water is reabsorbed back into the bloodstream, and unwanted ions are secreted, resulting in UROGENITAL THE a waste fluid known as urine. The remaining organs of the urinary system channel urine to the body’s exterior. They are the , urinary bladder, and . SYSTEM In contrast to urinary functions, the reproductive system performs the role of procreation. The sys- tem is unique in that the male and female structures are very different from each other, and are there- fore said to exhibit sexual dimorphism. In the female, the reproductive organs are highly adapted for the production of the female gametes (ova) and for the internal fertilization process, the internal incu- bation of the developing and fetus, and the birth process. In the male, reproductive organs are adapted for the production of the male gametes (spermatozoa) and for the internal semination process. In this chapter, you will examine the urogenital system of the cat through dissection. The chapter begins with a study of the urinary system. Then, you will study the reproductive systems, including that of both sexes.

The Urinary System remainder of your study of the urogenital system. With your cat specimen lying on its dorsal side, Note that the kidneys are not suspended within locate the following organs and features of the the abdominal cavity, as are the visceral digestive urinary system. The urinary organs include the organs, but lie outside the parietal peritoneum. This positioning is calledwww.eig.net retroperitoneal. Also kidneys, ureters, urinary bladder, and urethra. Figure 6.6 note the position of theOUTERNET adrenal Publishing glands, which lie Kidneys slightly cranial and medial to each . Carefully remove the fat from one of the kidneys, The kidneys are bean-shaped organs that lie section it along the frontal plane, and identify the partially embedded in fat against the dorsal body following features (Figure 7.1). wall (Figures 7.1, 7.2, and 7.3). To observe them, you must first push the visceral digestive organs RENAL : the outer layer of connective completely to one side. If you are dissecting on tissue that anchors each kidney to the dorsal a wax tray, pin these organs to the tray for the abdominal wall. 116 Chapter Seven

Renal

Renal

Renal

Renal

Ureter Renal pyramid

Renal column © bluedoor, LLC Figure 7.1 – Kidney (sectioned along the frontal plane).

RENAL CAPSULE: a thin layer of transparent , and the apices, or renal papillae, fibrous connective tissue that encloses each point to the . The areas between kidney and is deep to the renal fascia. adjacent renal pyramids are called renal col- : a depression near the center of each kid- umns. The is composed of ney’s concave medial border through which blood vessels and renal tubules (lengths of the renal , renal , lymphatic vessels, tubes that form part of the ). and nerves enter or exit. RENAL PELVIS: a membrane-lined basin in the Ureters center of each kidney, which unites with the The paired ureters are narrow tubes that transport mucous membrane lining the . Along urine from the hili of the kidneys to the urinary its borders are cup-like extensionswww.eig.net known bladder at the base of the pelvic cavity (Figures 7.2 as calyces, including major and minor.Figure 7.1 The OUTERNET Publishingand 7.3). Each ureter arises from the renal pelvis of calyces receive newly formed urine and chan- a kidney, and courses caudally in a retroperitoneal nel it into the center of the renal pelvis. pathway until it unites with the dorsal wall of the RENAL CORTEX: the outermost region of the bladder. Along the surface of each ureter is a thin kidney. It is relatively smooth in texture, and layer of fibrous connective tissue that is continu- outlines the internal periphery. The renal ous with the of a kidney. Carefully cortex extends from the renal capsule to the pick away any remaining connective tissue and fat internal region of the kidney, the medulla covering one of the ureters to expose it. In males, (described next). The cortex is composed another small tube, the , coils around of blood vessels and renal corpuscles (ball- the ureter near the base of the urinary bladder; shaped components of nephrons that contain avoid damaging the vas deferens for later study. the filtration apparatus). RENAL MEDULLA: the inner region of the kid- Urinary Bladder ney . It includes from six to eigh- Follow the path of the ureters to their caudal teen triangular, striated structures called renal extremities. Here they unite with the sac-like uri- pyramids. The bases of the pyramids face the nary bladder (Figures 7.2 and 7.3). The urinary The Urogenital System 117

Adrenal glands

Kidney

Ureter

Fundus THE UROGENITAL THE

Urinary bladder

Neck SYSTEM Inguinal canal

Seminal vesicle

Prostatic urethra gland

Spermatic cord

Membranous urethra

Bulbourethral gland Vas deferens Crus of Fascial sheath

Head Penis Prepuce Epididymis Body Glans penis Tail Testis

Figure 7.2 – Urogenital system of the male cat. © bluedoor, LLC

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Figure 7.2 OUTERNET Publishing 118 Chapter Seven

Adrenal glands

Kidney

Mesosalpinx Uterine tube Infundibulum

Ureter

Horn

Body

Urinary bladder Round ligament

Cervix of uterus Urethra

Urogenital sinus

Anal gland Urogenital aperture Anus © bluedoor, LLC

Figure 7.3 – Urogenital system of the female cat.

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Figure 7.3 OUTERNET Publishing The Urogenital System 119

bladder is a reservoir for urine. In the preserved Male Reproductive Structures state, it is empty and reduced in size, but when The organs of the it fills with urine, it expands about 5-fold. The include the male , known as the testes, expanded cranial portion is the fundus, and the which are located within the . They narrow caudal portion is the neck. Section the also include the penis, a series of tubes that carry bladder along the frontal plane and note the spermatozoa and fluids collectively called semen, wrinkled texture of the internal surface. These and the glands that produce the fluid. The tubes “wrinkles” are called rugae. Also note the points include the epididymus, vas deferens, and ure- of entry of the two ureters at the dorsal wall and thra, and the glands are the , pros- the exit opening to the urethra. These three tate gland, and bulbourethral gland. Locate the openings form an internal triangle known as the following components of the male reproductive trigone. The bladder is held in position ventrally system in your male specimen (Figure 7.2). by a median ligament and on each side by lateral , and is protected by pads of fat. Scrotum The scrotum lies hidden beneath the fur of the Urethra region caudal to the penis and ventral to the pel- The urethra is the duct that transports urine from vis. It is an integumentary sac that hangs below the urinary bladder to the exterior of the body. the pelvic wall and contains the male gonads (sex Because the urethra lies mainly in the pelvic organs), the testes. Carefully make a cut through canal, you will observe it during dissection of the the dorsal wall of one side of the scrotum and, reproductive system (Figures 7.2 and 7.3). The using scissors, cut the skin to the ventral margin.

urethra exhibits sexual dimorphism because its Repeat this cut on the opposite side. Now, peel UROGENITAL THE length varies between males and females. In the the skin away to expose the two testes. Note

female, it is a short duct that empties to the exte- the median septum that divides the scrotum SYSTEM rior by way of the urogenital orifice. The caudal internally in half, providing a separate chamber portion of the female urethra is also the caudal for each testis, known as the cremasteric pouch. portion of the vagina, and is called the vaginal Notice that the pouch narrows into a tubular vestibule (or ). The male urethra structure at its ventral end. This structure is the is much longer, extending from the urinary blad- , which contains the vas deferens, der to the tip of the penis, where it opens as the the spermatic artery and vein, and nerves. urogenital orifice. The male urethra is associated with both urinary and reproductive functions, Testes since it transports urine and semen. It is divided The paired testes are the organs that produce into three portions: the proximal portion is the the male gametes, or sex cells, and the male sex , the middle portion is the mem- , . Their outer coat, called branous urethra, and the distal portion extending the tunica albuginea, gives the testes a white, through the penis is the . The marbled appearance. With a sharp scalpel, cut human urethra is very similar, except it opens to the one testis in half and notice the coiled tubules exterior as the . within. These are the seminiferous tubules and are the site where the male gametes, called sper- The Reproductive System matozoa, are produced.

Your study of the reproductive system is divided into the male and female systems. On the basis of the descriptions that follow, determine the sex of your specimen, if you have not yet done so, and follow the appropriate dissection protocol. Then locate a specimen of the opposite sex within your lab, and examine it also. 120 Chapter Seven

Epididymus a sharp scalpel, cut into the depression and adja- On the dorsal part of each testis is an arrange- cent muscles. Plunge the scalpel deeply as you ment of tightly coiled tubules known as the cut. Now separate the pelvic bones by grasping epididymus. Locate the epididymus of your cat the hind limbs and push them laterally, complet- on the unsectioned testis. It is a comma-shaped ing the separation of the pelvis. Clean up the organ that curves around the dorsal margin of the area by removing connective tissue and fat. With testis. From ventral to dorsal, it is divided into a good technique, you should now be observing the head, a body, and a tail. The coiled tubule that organs of the pelvic wall, including the seminal forms the main part of the epididymus is called vesicles at the base of the bladder and the whit- the ductus epididymus, which extends from the ish prostate gland immediately ventral to it. The head region to the tail region, where it continues tube extending from the urinary bladder to the as the vas deferens. prostate gland, emerging to extend through the penis, is the urethra. As described previously, it Vas Deferens consists of a prostatic urethra, a membranous The vas deferens, which may also be called the urethra, and a spongy urethra. The prostatic ductus deferens, extends from the epididymus to urethra is the proximal portion, extending from the urethra. From each testis, it begins as a coiled the urinary bladder through the prostate gland. tube at its union with the ductus epididymus and The and spongy urethra continues in a cranial direction into the ventral are also known as the urogenital urethra. The body wall along with the spermatic artery, vein, membranous urethra extends a short distance to and nerves as the spermatic cord. Follow the vas the base of the penis. It receives secretions from deferens to its point of entry into the body wall. a small gland known as the bulbourethral gland, Note that it passes through an opening called the which contributes to semen. The spongy urethra inguinal canal. Once within the body cavity, it extends through the penis. It opens to the exte- passes ventrally toward the ureter and turns medi- rior at the urogenital orifice, ally until it reaches the dorsal wall of the urinary which is called the bladder. Do not attempt to trace the vas deferens urinary meatus in humans. further at this point in the dissection; you will need to open the pelvic cavity, which will be Penis done soon. At the base of the bladder is a mem- The penis of the cat is obscured by a sheath of branous, elongate sac called the seminal vesicle, skin, which surrounds it. To observe the penis, which empties its secretions into the vas deferens grasp the opening of the sheath with a pair of via a small duct. Near the neck of the bladder, forceps and make a cut through its ventral wall the vas deferens passes with its counterpart from with scissors. Continue this cut along the ventral the opposite side to the prostate gland, which is wall of the sheath, cutting through connective a glandular thickening of the dorsal wall of the tissue to expose the penis completely. Of course, seminal vesicle. The seminal vesicle and the pros- be careful to avoid cutting the penis at this point. tate contribute fluids to form the semen. The vas The penis encloses the spongy urethra, which deferens then passes through the prostatic tissue lies outside the pelvic canal. The free end of the to unite with the urethra near its origin from the penis, called the glans penis, lies within a pocket bladder. of skin called the prepuce. Cut open the prepuce to reveal completely the glans and the opening of Urethra the spongy urethra. Then cut through the penis To observe the urethra and the male glands that along the longitudinal plane. Notice the columns contribute to semen, it is necessary to cut through of erectile tissue, which contain blood sinuses that the pubis. To do this, carefully make fill with blood to produce erection. The columns a 2.5-cm-long (1-inch) incision through the are called corpora cavernosa. Their proximal abdominal wall along the margin of the pelvis. ends are attached to the ischia by tough bands With your fingers, find a slight depression in of connective tissue, known as crura (crus in the the midline between the pubic bones and with The Urogenital System 121

singular form). The is not contained called the infundibulum and opens medially by within a sheath as in the cat, but hangs freely from way of the ostium tubae. The outer margins of its attachments to the by way of the the infundibulum contain finger-like projections, crura. called fimbriae. Each uterine tube is attached to The reproductive system of the cat includes the dorsal body wall by a broad ligament known anal glands, which are located near the anus. In as the . The distal end of each uter- male cats, contraction of the glands and nearby ine tube merges with a uterine horn, which is muscles causes fluid to spray outward, marking larger in diameter. The uterine tubes of the human the cat’s territory. female are comparatively much greater in length, extending from the infundibulum surrounding an Female Reproductive Structures ovary to the pelvic cavity to unite with the uterus. The female gonads are the . Other female organs include the uterine tubes, uterus, vagina, and . Locate and identify the following Uterus components of the female reproductive system in The uterus of the cat includes two uterine horns, a female cat (Figure 7.3): right and left, that begin as continuations of the uterine tubes. They descend into the pel- Ovaries vic cavity, where they unite to form the body The ovaries are paired, oval organs that lie slightly of the uterus. The combination of the uterine caudolateral to the kidneys in the abdominopelvic horns and body form the Y-shaped uterus. The cavity. They are anchored to the ventral body mesentery supporting the uterus is known as

wall by the suspensory ovarian ligament and to the mesometrium, and an additional structure, UROGENITAL THE the dorsal body wall by the larger ovarian liga- called the round ligament, adds strength to the

ment. The ovarian ligament connects each ovary mesometrium as it extends diagonally across it. SYSTEM to the cranial end of the uterus. A third ligament, The distal end of the uterus is slightly tapered, the mesovarium, provides an additional connec- forming the , which unites with the vagina. tion between each ovary and the corresponding The uterus of the human female is not Y-shaped, but uterine horn. As the female gonads, the ovaries resembles the shape of a pear, instead. It receives the produce the female gametes, the ova, and the right and left uterine tubes at its superior border, female sex , and . which is a rounded area known as the fundus. The During ovulation, or release of an ovum from an constricted part of the uterus is known as the cervix, ovary, the ovum bursts through the ovarian wall and its internal channel is the cervical canal. Also, to enter the abdominal cavity. Ideally, the ovum the junction of the uterus and vagina is a distinct is then swept into the nearby opening to the uter- separation between the two organs. ine tube by ciliary currents. Vagina Uterine tubes To view the vagina and other caudal parts of the Also known as , or fallopian tubes, the reproductive system, you will need to expose the paired uterine tubes transport ova that have been pelvic cavity. Begin by making a 2.5-cm-long released during ovulation from the ovaries. If (1-inch) incision horizontally along the pelvic fertilization is to occur, it usually occurs within rim, cutting through muscles and fat. Insert a the upper one-third of a uterine tube. The fertil- finger to find the symphysis pubis, which will ized ovum, called a zygote, is then transported feel like a shallow groove near the midventral by ciliary currents within the tube to the uterus line. Once you’ve located it, cut through it with for implantation. Carefully reflect the ovary and a pair of scissors or bone cutters, but be careful to uterine tubes to the side, and notice that the cra- avoid plunging the instrument too deeply. You nial extremity of each uterine tube curves laterally will be cutting through deep muscles and the over each ovary to form a hood-like expansion of the symphysis pubis, if you are cut- 122 Chapter Seven

ting correctly. After cutting, grasp the hindlimbs the urogenital aperture on both sides are the small and separate the pelvic bones to expose the pelvic labia, which are very small in the cat and, there- wall. Carefully clean away connective tissue and fore, difficult to observe. However, you should fat, and find the body of the uterus once again. be able to identify the clitoris, represented as a Trace it to its narrowed distal part, the cervix, small projection at the cranial union of the labia. which protrudes into the vagina. The vagina It rests in a shallow, midventral depression. The extends from its origin near the cervix to its open- clitoris is the homologous structure to the penis, ing to the urogenital sinus at the vaginal orifice. although in most mammals, the urethra does Because the urogenital sinus also receives the not pass through it. Similar to the male, anal opening of the urethra, the urethral orifice, it is glands are present on either side of the anus. The a common channel for the urinary and reproduc- human vulva contains two pairs of labia, majora tive fluids. and minora, rather than a single pair, as seen in the cat. Also, the human clitoris is a more prominent Vulva structure. Finally, the urethra and vagina enter the The vulva is the female external structure that vulva as separate openings in human females: as the includes the urogenital aperture, labia, and clito- urethral orifice and the vaginal orifice. ris. The urogenital aperture is the exterior open- ing from the urogenital sinus, which is common to the urinary and reproductive systems. Bordering The Urogenital System 123 Chapter Review

A. Answer the following multiple-choice questions by circling the most correct answer.

1. The urogenital organs that function in the formation of urine are the a. urethra b. kidneys c. spleen and thymus d. ureters and urinary bladder

2. Organs that have a different structure between males and females are a. called sexually dimorphic b. the ureters c. the kidneys d. the urinary bladder

3. The blood becomes filtered, water is reabsorbed, and excess ions are secreted within a. the gonads b. nephrons c. the renal pelvis d. ureters

4. Renal pyramids may be found within the a. renal capsule b. renal medulla c. renal cortex d. renal pelvis

5. From the ureters, urine flows into the UROGENITAL THE a. urinary bladder b. renal pelvis

c. urethra d. kidneys SYSTEM

6. In the female cat, the urethra opens to the exterior as the a. vagina b. urogenital orifice c. urinary meatus d. urethral orifice

7. The dorsal part of each testis is an arrangement of tightly coiled tubules known as the a. vas deferens b. seminal vesicles c. epididymus d. spermatic cord

8. Near the neck of the bladder, the vas deferens passes with its counterpart from the opposite side to the a. epididymis b. prostate gland c. seminal vesicles d. ureter

9. As the female gonads, the ______produce the female gametes called ova. a. testes b. uterus c. ovaries d. fallopian tubes

10. The distal end of the uterus is slightly tapered, forming the______, which unites with the vagina. a. vas deferens b. cervix c. uterine cavity d. vestibule 124 Chapter Seven

B. Complete the sentences below by providing the missing terms from the chapter material.

1. Urine formation occurs in the kidneys, at the site of functional subunits called ______.

2. The ______is a membrane-lined basin in the center of each kidney, which unites with the mucous membrane lining the ureter.

3. The three openings into the urinary bladder form an internal triangle known as the ______.

4. The ______is the duct that transports urine from the urinary bladder to the exterior of the body.

5. The integumentary sac that hangs below the pelvic wall and contains the testes is called the ______.

6. The coiled tubules within the testes, where spermatozoa are produced, are called ______.

7. The ductus epididymus continues as a tube of larger diameter known as the ______.

8. Each ovary is supported to the dorsal body wall by the ______.

9. The uterus of the cat includes two ______, right and left, that begin as continuations of the uterine tubes.

10. The ______is the exterior opening from the urogenital sinus in the female cat, which is common to the urinary and reproductive systems.

C. Answer the following descriptive and critical-thinking questions with a brief explanation in the spaces provided.

1. Describe the functional importance of nephrons and where they are located. ______

______

______

______

______

______

______The Urogenital System 125

2. Trace the pathway of spermatozoa during an . ______

______

______

______

______

______

3. Compare and contrast the vulva of a cat and a human. ______

______

______

______

______UROGENITAL THE

______SYSTEM

______

127

chapter eight THE AND SPECIAL

The nervous system provides a system of communication between its primary organ, the , and the distant parts of the body. Its goal is to monitor changes in the environment inside and outside the body, interpret the changes, and initiate a response in an effort to maintain homeostasis. It does all of this by way of electrochemical messages called impulses. Nerve impulses race through the body every moment, traveling along special routes, or nerves, at high speeds. As a whole, the nervous system is a complex series of organs and structures that extend throughout the body. In addition to the brain, its organs include the , nerves, ganglia, and sensory receptors. The nervous system is divided into two main categories: the (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes the nerves, ganglia, and sensory receptors. The PNS is further divided in an afferent (sensory) system, which carries impulses from receptors to the CNS, and an efferent (motor) system, which carries impulses from the CNS to effectors, such as muscles and glands. The efferent system is itself divided into a somatic system, in which impulses are carried to skeletal muscles, and an autonomic system,

which carries impulses to glands and smooth muscles. Finally, the autonomic system is divided into SENSES SPECIAL THE NERVOUS NERVOUS THE a sympathetic division and a parasympathetic division. AND SYSTEM This chapter enables you to explore the structures of the nervous system of the cat. You will remove the brain from the to examine it, observe the spinal cord, and trace the major nerves throughout the body. You will also examine the special sensory organs, which are associated with the nervous system. They include the , , taste organs of the tongue, and smelling centers in the nasal .

Central Nervous System , they are the outer dura mater, the middle arachnoid, and the innermost . The central nervous system, which includes the brain and spinal cord, represents the center of 1. Clean the dorsal and neck regions nervous system structure and function. You will completely of skin, muscle, and connec- study the brain of the cat first, which requires tive tissue. www.eig.net removal of the brain from the cranial cavity. In Figure 6.6 OUTERNET Publishing some labs, the cat brain may be substituted for a 2. Using a pair of sharp bone shears, cut the sheep brain. Because both are typical of a mam- 3rd, 2nd, and 1st cervical vertebrae, and malian brain, either is suitable for this study. remove the bone fragments with forceps. To remove the brain from the cranium of your Sever the spinal cord with a clean cut as cat, follow the protocol outlined below. As you far caudally as possible. progress through this procedure, identify the three membrane layers that surround the brain 3. Very carefully insert the pointed half of and spinal cord. Collectively known as the your bone shears slightly through the 128 Chapter Eight

foramen magnum at the base of the skull, is separated from the arachnoid by a but don’t go too deep! Close the shears fluid-filled space called the subarachnoid and apply pressure. This should crack the space, which is continuous around the thick occipital bone. brain and spinal cord. A slightly yellow- ish fluid circulates within this space to 4. From the cracked occipital bone, cut provide a cushion for the CNS, around the skullcap above the eye orbits and is known as with bone shears, but again be very care- (CSF). ful to avoid cutting too deeply. Once you’ve cut a complete circle, carefully lift 6. To remove the brain from the cranial the skullcap off. Note the tough dura cavity, begin by lifting the severed spi- mater that covers the brain. The out- nal cord from the floor of the vertebral ermost of the meninges, it is composed canal. Then lift the brain from the floor of tough, fibrous connective tissue. In of the cranial cavity by working caudally some areas, it is connected to the inner and very cautiously. As you do so, sever surface of the skull, and, thus, may have the cranial nerves from the brain with a been damaged as you cut through the sharp scalpel (this is a good job for a cranium. Carefully pull the dura mater partner if one is available). Make your away from the brain to expose the under- cuts as far from the brain as possible to lying meningeal layers, and make a cut facilitate their identification later. through it with a scalpel from rostral to caudal. As you do so, note the exten- Brain sion of the dura mater between the two The mammalian brain contains three primary cerebral hemispheres, which is called the divisions: the , the , and the falx cerebri, and the extension between . Before identifying the structures of the and the cerebellum, known the brain, many of which require sectioning of as the tentorium. These membranes the brain in half to observe, turn the brain on its help anchor the brain within the cranial dorsal side to expose the ventral surface. Using cavity. Table 8.1 as a reference, identify the cranial nerves, whose cut ends should be visible as shown 5. Using a pair of forceps, carefully remove in Figure 8.1. Following this exercise, observe the the remaining pieces of bone. In the parts of the brain as described. caudal section of the cranial cavity, cut out and remove the small bone seg- FOREBRAIN (prosencephalon): the largest divi- ments protecting the delicate cerebellum. sion of the brain. Occupying the cranial and Continue to remove bone pieces until middle regions, it consists of the large tel- the brain is well exposed. With the dura encephalon and the much smaller diencepha- mater removed, note the meningeal layer lon (Figures 8.1 - 8.3). beneath it, known as the arachnoid. It Telencephalon: consists of the largest single is composed of structure of the brain, the cerebrum. arranged in a cobweb-like arrangement. The cerebrum is convoluted in the The arachnoid passes over the shallow cat, although much more so in the grooves, or sulci, of the brain’s surface. human. Note the downfolds, or The upfolds of the brain are called gyri. sulci, and the upfolds, or gyri. The With your forceps, pick away the thin cerebrum consists of two halves, the membrane adhering to the surface of right and left cerebral hemispheres, the brain. This is the deepest meningeal which are separated by a deep fur- layer, the pia mater. The pia mater row called the longitudinal fissure. The Nervous System and Special Senses 129

Cranial Nerve Union with Brain Innervations Sensation or Action Olfactory (I) olfactory lobe sensory endings in nasal of olfaction epithelium (smell) Optic (II) rostral colliculi and sensory cells in the sense of vsion (sight) retina of each eye Oculomotor (III) cerebral peduncles of intrinsic and extrinsic movement of eye, midbrain eye muscles control of light enter- ing eye Trochlear (IV) roof of midbrain superior oblique muscle movement of eye of eye Trigeminal (V): lateral portions of pons external eyeball, skin of sensations of face region 1. Ophthalmic skull sensations of rostrum 2. Maxillary vibrissae and upper teeth movement of jaw; 3. Mandibular jaw, skin of lower face, sensations of lower face teeth of lower jaw, and mouth mouth, tongue

Abducens (VI) rostral end of medulla rectus externus muscle movement of eye of eye

Facial (VII) medulla caudal to CN jaw and face muscles mastication and facial SENSES SPECIAL THE NERVOUS NERVOUS THE VI expression AND SYSTEM Auditory (VIII) lateral medulla sensory cells within sense of audation cochlea of inner ear (hearing) Glossopharyngeal (IX) lateral medulla pharynx, parotid gland, sense of gustation caudal portion of (taste), sensations of tongue throat region Vagus (X) lateral medulla muscles of the pharynx, contraction of larynx, thoracic viscera, innervated muscles; abdominal visceral; sensation of innervated sensory of larynx, and regions thoracic and abdominal viscera

Spinal accessory (XI) lateral medulla muscles of the neck and movement of the neck pharyngeal region and pharynx

Hypoglossal (XII) ventral medulla tongue and hyoid movement of the muscles tongue

Table 8.1 – The cranial nerves. 130 Chapter Eight

Olfactory bulb Cranial Nerves

CN Olfactory tract I

Optic chiasma CN II Infundibulum

CN III

CN IV CN V Cerebral peduncle CN VI CN VII CN VIII Pons CN IX CN X CN XI

Ventral fissure CN XII © bluedoor, LLC Figure 8.1 – Cranial nerves (ventral aspect of the brain).

Separate the hemispheres by spread- the brain (two , one ing them apart with your fingers, , and one fourth ven- and you will see a thick, transverese tricle; you will identify the third and band of that connects fourth ventricles a bit later). They the hemispheres. This bridge is the contain clusters of and corpus callosum. Now make a mid- ventricular cells. The clusters are sagittal section through the brain by known as choroid plexi, which serve cutting deeply through the longitu- as the source of cerebrospinal fluid dinal fissure. Use a long, sharp knife (CSF). The septum pellucidim may

for this procedure to make a single,www.eig.net be visible, which is a thin membrane

clean cut through the brain. TheFigure cor -8.1 separating the two lateral ventricles. pus callosum includes an expandedOUTERNET Publishing At the rostral end of the cerebrum is rostral end, called the genu, a thin- located a pair of swellings, called the ner middle section known as the olfactory lobes. They represent the trunk, and an expanded caudal end terminal points of olfactory nerves known as the splenium. The ven- originating from the nasal epithe- tral continuation of the splenium lium. The Olfactory Nerves (CN I) is called the fornix. Immediately extend from the olfactory lobes to inferior to the corpus callosum is a the cerebrum. A second deep furrow, cavity, called the lateral ventricle, called the transverse fissure, sepa- which is one of four ventricles in rates the cerebrum from the smaller The Nervous System and Special Senses 131

cerebellum located on the caudal side ter for autonomic functions and trig- of the brain. The cerebrum is the gers the pituitary gland (hypophysis) integrative center of the brain. It that is attached to it via a narrow receives sensory information, pro- stalk. A second , cesses it with memory connections, the , is the small, round and initiates motor responses. Its structure that projects from the roof primary functional zone is the outer of the . Ventral to the fringe of gray matter, known as the pineal gland is the third ventricle. cerebral cortex. White matter is It receives CSF from the two lateral found deep to the cortex, which ventricles via a small channel called serves as communication pathways. the foramen of Monro. Turn the Embedded within the white matter brain over to expose the ventral sur- of both hemispheres are islands of face, and find the X-shaped optic gray matter called the basal ganglia. chiasma. It is the crossing of the two Diencephalon: the region of the brain Optic Nerves (CN II). located ventral to the cerebrum and MIDBRAIN (mesencephalon): a small part of immediately below the lateral ven- the brain, which is located ventral to the fore- tricles. Its most prominent structure brain (Figure 8.3). Its major portions are the is the bilobed thalamus, which forms tectum and the cerebral peduncles. the central portion and lateral walls Tectum: forms the roof of the mid- of the diencepahlon. The thalamus brain, and can be observed as is a switchboard for impulses travel- the swellings in the center of ing to and from the cerebrum. At its the brain rostral to the cerebel- ventral border is the much smaller lum. The swellings are the corpora , which serves as a cen- quadrigemina. The larger rostral SPECIAL SENSES SPECIAL THE NERVOUS NERVOUS THE

Olfactory lobe AND SYSTEM

Cerebral hemisphere

Longitudinal fissure Gyrus Sulcus

Transverse fissure Flocculi

Vermis Cerebellar hemisphere Folia

Sulci Medulla oblongata © bluedoor, LLC Figure 8.2 – Brain (dorsal aspect).

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Figure 8.2 OUTERNET Publishing 132 Chapter Eight

Corpus callosum

Genu Trunk Splenium Lateral ventricle (with choroid plexus) Cerebral Pineal gland hemisphere (of tectum) Arbor vitae

Septum pellucidum

Fornix Optic chiasm Medulla Spinal cord Velum Third ventricle Pons oblongata Thalamus Pituitary gland © bluedoor, LLC Figure 8.3 – Brain, midsagittal section (lateral view).

pair is called the rostral colliculi, and culi. The outer surface, which is the smaller caudal pair is the caudal composed of gray matter, is called colliculi. the cerebellar cortex. The ventral Cerebral peduncles: a pair of fiber bun- component of the dles that form the ventrolateral sur- is formed by a rounded swelling at face of the midbrain. the cranial end of the brain stem, HINDBRAIN (rhombencephalon): the caudal called the pons varolii. The pons part of the brain, it consists of the met- is connected to the cerebellum by encephalon and the myelencephalon (Figures transverse fibers. 8.2 - 8.3). Myelencephalon: the caudal part of the

Metencephalon: the cranialwww.eig.net part of midbrain, which is also the caudal

the hindbrain. The cerebellumFigure 8.3 dom- extremity of the brain. The myel- inates most of the metencephalon,OUTERNET Publishing encephalon includes the medulla forming the dorsal component. Its oblongata, which is the transitional surface area is increased by numer- region between the brain and the ous folds, known as folia, which are spinal cord. Together with the separated from each other by shal- pons varolii and midbrain, the low grooves, or sulci. The central three brain structures form the portion of the cerebellum, the ver- brain stem. The fourth ventricle mis, is composed by white matter, is located between the cerebellum as you can observe in the sectioned and the medulla. It receives CSF brain. Numerous branches of gray by way of the narrow cerebral matter extend from it to the outer aqueduct (aqueduct of Sylvius), surface. This branching arrange- which runs through the midbrain. ment is called the arbor vitae (tree of life). Lateral to the vermis are the Spinal Cord right and left cerebellar hemispheres The spinal cord is a semicyclindrical mass of gray and their lateral extensions, the floc- and white matter enveloped by the meninges The Nervous System and Special Senses 133

(Figure 8.4). Beginning at its cranial end as a segment where it fuses with the pia caudal continuation of the medulla oblongata, mater; the middle arachnoid; and the it passes through the vertebral canal and tapers deep pia mater, which adheres to the at the 7th lumbar segment to a bundle of nerves surface of the spinal cord. Similar to called the . The spinal cord termi- the brain meninges, the arachnoid nates as a slender filament, the filum terminale, and pia mater are separated by the in the base of the tail. In the cervical and lum- subarachnoid space, in which CSF bosacral regions, the spinal cord contains swell- circulates. ings that give rise to the nerves that innervate the SPINAL CORD GRAY MATTER: the H-shaped front and hind limbs, respectively. mass of nerve tissue at the center of A pair of spinal nerves arise from each segment the spinal cord. The gray matter of and exit the via intervertebral the cord consists of the gray com- foramina. The spinal nerves are named according missure, which is the central bridge to the region of the vertebral column where they connecting the left and right sides arise. A is formed by the union of a of the H; the anterior (ventral) gray ventral root and a dorsal root. After exiting the horns, located on the ventral side of vertebral column, the spinal nerve divides into a the spinal cord and which form the dorsal ramus, which supplies the muscles of the larger of the two horn segments of back, and a thicker ventral ramus, which supplies the H; the posterior (dorsal) gray the remaining somatic muscles of the body. horns, located on the dorsal side of You should not attempt to remove the entire the spinal cord; and the lateral gray spinal cord of your cat at this time, because of the horns, located between the anterior damage this dissection would cause to spinal and and posterior gray horns. Note also peripheral nerves. Instead, obtain a cross section the small hole in the center of the of the cord by cutting off the caudal tip of the gray commissure. This is the central region below the brain stem of the brain. Using canal, which runs the entire length of SPECIAL SENSES SPECIAL

this section, locate the following components of the cord and carries CSF. NERVOUS THE SYSTEM AND AND SYSTEM the spinal cord (Figure 8.5): SPINAL CORD WHITE MATTER: the white nerve tissue surrounding the gray MENINGES: continuous with the meninges of matter horns. The white matter the brain, the three membranes are consists of ascending tracts of sensory the outermost dura mater, which fibers and descending tracts of motor continues to the 2nd sacral vertebral nerve fibers.

Dura mater 7th lumbar Spinal cord (dissected open) segment of cord 1st lumbar n. 7th lumbar vert. 1st lumbar vert. 7th lumbar n. 13th thoracic n. Cauda equina 1st sacral n. Filum terminale © bluedoor, LLC Figure 8.4 – Spinal cord (dorsal view of dissected cord within vertebral column).

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Figure 8.4 OUTERNET Publishing 134 Chapter Eight

Dorsal fissure Spinal meninges: Dorsolateral sulcus Dura mater Posterior gray horn Arachnoid

White matter (funiculus) Pia mater

Gray commissure

Dorsal root Spinal ganglion Anterior gray horn Dorsal ramus Central canal Ventral ramus Ventral fissure Ventral root Gray matter Spinal nerve © bluedoor, LLC Figure 8.5 – Spinal cord (cross section).

Peripheral Nervous System the neck from the dorsal side as they emerge from the vertebral column. The peripheral nervous system (PNS) consists of BRACHIAL PLEXUS: located medial to the the motor (efferent) nerves that carry impulses shoulder and cranial to the 1st , it can from the CNS to PNS effectors, and the sensory be observed from the ventral side deep to (afferent) nerves that carry impulses in the oppo- the pectoral muscles. The brachial plexus site direction. The following study of the PNS is formed by the union of the ventral includes the somatic division of the PNS, which rami of the 5th to 8th cervical and 1st tho- contains the networks of nerves arising from the racic nerves. From the brachial plexus arise ventral rami that innervate skeletal muscles and the following nerves: a brief description of the autonomic division of Pectoral nerves: several small nerves that the PNS. www.eig.net arise from the ventral divisions of the Figure 8.5 plexus. OUTERNET Publishing Somatic Division Scapular nerves: two nerves, a scapular The somatic division of the PNS includes branch- and a suprascapular nerve, both of ing networks of nerves known as plexi, and the which arise mostly from the 6th cer- various peripheral nerves extending from the vical root. plexi to skeletal muscles. In the musculature of Axillary nerve: a large nerve located cau- your cat, locate the following plexi and major dal to the scapular nerves. It passes peripheral nerves (Figure 8.6): through the brachium ventral to the long head of the triceps. CERVICAL PLEXUS: the least extensive of the Subscapular nerve: two small nerves that three major plexi, it is formed by the ven- arise from the plexus near the origin tral rami of the cervical region. The nerves of the axillary and continue dorsal to associated with the cervical plexus supply the it. musculature and skin of the neck region. It Radial nerve: a large, deep nerve located can be located by tracing the ventral rami of caudal to the axillary. It is formed by The Nervous System and Special Senses 135

Scapular nerves Spinal nerve C1 Axillary nerve Cervical plexus Nodosal ganglion Radial nerve Crainal cervical ganglion Median nerve Ulnar nerve (X) Brachial enlargement

C5 Brachial plexus Cardiac plexus

Spinal nerve T1 Musculocutaneous nerve C6 Phrenic nerve Ganglion of C7 Radial nerve C8

Th1

Median nerve Coeliac ganglion Spinal nerve L1 Ulnar nerve Phrenic nerve

Genitofemoral nerve L4 Lumbosacral plexus Lumbosacral enlargement SPECIAL SENSES SPECIAL THE NERVOUS NERVOUS THE

L5 Femoral nerve Spinal nerve S1 AND SYSTEM Obturator nerve

L6 Femoral nerve L7 Cauda equina

S1 Sciatic nerve Sciatic nerve S2 Pundendal nerve S3

Figure 8.6www.eig.net – Nervous system of the cat. © bluedoor, LLC Figure 8.6 OUTERNET Publishing 136 Chapter Eight the union of the 7th and 8th cervical Autonomic Division and 1st thoracic nerves. The autonomic division of the PNS innervates Musculocutaneous nerve: arising from smooth muscles and glands. Its major com- the 6th and 7th cervical nerves, ponents include the following ganglia, rami, it passes superficial to the radial nerve and nerves, some of which are diagrammed into the brachium. in Figure 8.6. Autonomic components are Median nerve: a prominent nerve that divided into two distinct groups: the sympathetic runs down the medial side of the division, which carries impulses that activate brachium. It is a ventral division of body responses to emergency situations, and the the 7th and 8th cervical and 1st tho- parasympathetic division, which carries impulses racic nerves. that dominate when the body is at rest. Ulnar nerve: arising caudal to the median nerve, the ulnar is similar to the SYMPATHETIC TRUNK GANGLIA: a verti- median nerve in its pathway. cal row of ganglia, which are clusters of neu- LUMBOSACRAL PLEXUS: formed by the ron cell bodies, extending along both sides ventral rami of seven spinal nerves of the vertebral column from the base of the (4th lumbar to 3rd sacral), it supplies the skin skull to the tail. These ganglia receive sympa- and muscles of the pelvis and hind limbs. thetic fibers originating from the spinal cord. Because it lies deep within the abdominal Collectively, the sympathetic trunk ganglia and pelvic cavities, you will not observe it in are referred to as the sympathetic chain. your specimen. However, identify the follow- PREVERTEBRAL GANGLIA: also known as ing peripheral nerves that originate from this collateral ganglia, they are located ventral plexus in the hip and thigh musculature of to the vertebral column and close to large your cat. abdominal . Prevertebral ganglia : a division of the receive sympathetic fibers originating from 4th lumbar nerve, it passes caudally the spinal cord. through the pelvic wall. TERMINAL GANGLIA: also known as intra- Femoral nerve: a large nerve that arises mural ganglia, they are located at the end of primarily from the 5th and 6th lum- visceral efferent pathways near or on the walls bar nerves. It passes through the of visceral effectors, such as pelvic wall on the ventral side along and glands. The terminal ganglia receive with the femoral artery and vein. parasympathetic fibers that originate from Obturator nerve: arising from the unifi- the spinal cord. cation of a second division of the 6th COMMUNICATING RAMI: spinal nerve lumbar nerve and a second division branches that carry impulses to or from sym- of the 5th lumbar nerve, it extends pathetic trunk ganglia. In the thoracic and caudolaterally through the obturator upper lumber segments, they contain myeli- internus muscle and the obturator nated fibers to form the white communicat- foramen. ing rami, or nonmyelinated fibers to form the Sciatic nerve: a continuation of the lum- gray communicating rami. In the remaining bosacral trunk, which receives the vertebral segments all of the communicating 6th and 7th lumbar nerves and the rami are gray. 1st and 2nd sacral nerves. The sciatic VAGUS NERVE (X): a large cranial nerve that nerve continues down the lateral side was described previously. It contains sym- of the thigh to divide into the tib- pathetic and parasympathetic fibers that sup- ial and fibular (common peroneal) ply major thoracic and abdominal visceral nerves. organs. The Nervous System and Special Senses 137

PHRENIC NERVE: a large nerve that arises contain with dendrites that project onto from the ventral rami of the 5th and 6th cer- the surface of the papillae, and are sensitive to vical nerves and passes caudally through the dissolved chemicals. From the front, or oral, part thoracic cavity to innervate the diaphragm. of the tongue, impulses generated by the sensory neurons in the taste buds are transmitted via a branch of the facial nerve (CN VII). From the back, or pharyngeal, part of the tongue, impulses Organs of Special Sense are transmitted via the glossopharyngeal nerve The special senses are specialized parts of the body (CN IX). that provide the brain with information about the outside environment. There are four special Vision senses: olfaction (smell), gustation (taste), vision The eye lies within its protective bony orbit. (sight), and audation (hearing). The four special During your earlier observation of the cat’s senses are perceived with the help of highly spe- surface anatomy, you identified the palpebrae cialized organs. They are sensory patches within (eyelids) and the nictitating membrane. At this the nasal epithelium (olfaction), taste organs on time, identify also the conjunctiva, which is a the tongue (gustation), the eyes (vision), and the thin transparent membrane covering the under- ears (audation). In each case, the special sensory side of each eyelid and the surface of the eyeball. organ contains sensory receptors. The sensory Also, find the harderian gland, which is a small receptors are sensitive to a particular stimulus, gland on the medial surface of the nictitating and generate a nerve impulse when the stimulus membrane. Now, free the eyeball from the orbit is sufficiently strong. The nerve impulse then rim and push it forward to observe the lacrimal travels to the brain for interpretation. gland, which produces tears. Now push the eyeball dorsally until it can be extracted from the Olfaction orbit completely, and sever the optic nerve. Some of the extrinsic eye muscles will also require cut- The sense organs responsible for smell reception SENSES SPECIAL THE NERVOUS NERVOUS THE may be found within a patch of the mucosa lining ting. AND SYSTEM the nasal cavity. Located in the dorsocaudal part From Figure 8.7, identify the extrinsic eye of each nasal chamber, it is called the olfactory muscles, which move the eyeball. There are mucosa. The receptors in the ofactory mucosa are seven muscles: four recti originate on the bone olfactory cells. The hair cells include den- around the optic foramen and insert on the drites, which appear under the microscope like sclera (white exterior covering of the eyeball) tiny that project into the mucosal lining. just behind the midline, or equator, of the eye- When the hair cells make contact with dissolved ball. They are known as the superior, inferior, chemicals in the mucosa, they generate a nerve lateral, and medial recti muscles according to impulse. The impulse passes to adjacent sensory their position. A retractor muscle also originates neurons that form olfactory nerves, which extend from the optic foramen, and inserts on the sclera to the olfactory lobe. At the olfactory lobe, the around the entrance to the optic nerve. The two olfactory nerves synapse at sensory neurons, oblique muscles, the superior oblique and infe- which transmit the impulse to the cerebral cortex rior oblique, are evident only if the lateral and for interpretation. dorsal walls of the orbit are removed. With one eye from your cat removed, observe Gustation its external features. Then, using a sharp scalpel, cut it into two equal parts along the equatorial The taste receptors are organized into specialized plane. Since the internal structures of the eye are groups of cells, known as the taste buds. Most difficult to observe in a cat, you may be asked to taste buds are located on the fungiform and cir- study a preserved or fresh cow eye instead, which cumvallate papillae of the tongue. Taste buds is anatomically similar. The eye includes the 138 Chapter Eight

ing from the ciliary body, located behind the

Sclera pupil. Normally transparent, it is composed Superior rectus of dense protein formations. Immediately behind the lens is the posterior chamber, Retractor bulbi Iris which contains a gelatinous vitreous humor. Lateral rectus Cornea RETINA: the innermost layer of the eyeball lin- ing the posterior wall. It contains specialized Pupil sensory receptors, known as rod cells and

Optic nerve Lens cone cells, which generate a nerve impulse when they become activated by light. From the rods and cones, the nerve impulse is

Inferior oblique passed to two additional layers of neurons, the last of which converge at the optic disc to form the optic nerve (CN I). The optic nerve carries the impulse to the thalamus, and relays it to the occipital lobe of the cerebral © bluedoor, LLC cortex, where the impulses are interpreted Figure 8.7 – External eye with extrinsic muscles into the sense of vision. (lateral view). following major structures, some of which are Audation illustrated in Figure 8.7: The ear contains the sense organs for both hear- ing and equilibrium. It consists of three parts: the SCLERA: the white outer layer of the eyeball, external ear, the middle ear, and the internal ear. which is composed of fibrous connective tissue. The sclera provides support for the EXTERNAL EAR: the part of the ear exposed eyeball. to the external environment. It includes the CORNEA: a rostral continuation of the sclera following components: that is transparent. The conjunctiva meets Pinna: also known as the auricle, it is the www.eig.net

the cornea alongFigure 8.7 its outer edge. The anterior external appendage on each side of chamber is locatedOUTERNET Publishing immediately behind the the head of mammals. The pinna cornea. funnel mechanical vibrations (sound IRIS: the pigmented ring of smooth muscle, waves) into the head. Each consists which surrounds the black central hole. of cartilage that is covered with skin, Involuntary impulses regulate contraction and is connected to extrinsic auricu- of the iris, which serves as a diaphragm to lar muscles whose contraction moves regulate the amount of light that enters the the pinna in the direction of sound. interior of the eye. External auditory meatus: a skin-lined PUPIL: the black hole in the center of the iris, canal extending from the pinna to through which light enters the eye. the tympanic membrane. It includes CHOROID: a vascular, black pigmented layer ceruminous glands, which secrete a internal to the sclera. It helps to nourish the waxy substance that lubricates the retina, and the pigments reduce the scattering meatus and traps foreign particles. of light rays to improve visual efficiency. Tympanic membrane: a thin membrane CILIARY BODY: a series of folds, forming a that separates the interior end of the thickened ring within the eyeball between the external auditory meatus and the choroid and iris junction. middle ear. It vibrates in response LENS: the large oval or spherical structure that is to sound waves, and transmits the suspended by suspensory ligaments extend- vibration to the middle ear . The Nervous System and Special Senses 139

MIDDLE EAR: the cavity within the tympanic INNER EAR: a series of winding canals sur- bulla of the skull, which is also known as the rounded by bone within the mastoid portion tympanic cavity. Dissection of the middle of the temporal bone, it is also called the ear is extremely difficult, and is not recom- labyrinth. It consists of an outer series of mended unless time and advanced dissection canals within walls of bone, known as the skills are available. If you wish to attempt it, bony labyrinth, and an inner series of canals you will remove the tympanic bulla from the lined with membrane, called the membra- cranium. To do this, first prepare the area nous labyrinth. In life, fluid is present in by removing all soft tissues around the tym- each canal. Because of its very small size, the panic bulla. Using bone shears, cut through inner ear is extremely difficult to dissect. But the bulla and medial (petrous) portion of the if you wish to attempt it, it can be done by temporal bone from the skull. Next, remove carefully chipping away the temporal bone the medial wall of the tympanic bulla by cut- medial to the tympanic cavity. With patience ting with bone shears. Notice that the cavity applied, you will gradually find the bony within the bulla is separated into a larger labyrinth embedded within the bone of this lateral and a smaller medial chamber by a region. Using Figure 8.8 as a guide, identify vertical wall of bone. Carefully break away the following parts of the inner ear: this vertical plate of bone to expose the lat- Cochlea: a coiled, snail-shell-like part of eral chamber, which reveals the inner surface the labyrinth that contains hair cells, of the tympanic membrane and its attached which are the sensory receptors for middle ear ossicle (the malleus). Then, audation. The hair cells are sensory with your bone shears, fracture the thick neurons with dendrites, which gener- bony connection between the caudal end of ate a nerve impulse when the fluid the petrous bone and the caudal part of the surrounding them moves in response bony ring surrounding the external auditory to mechanical vibrations. meatus. Using Figure 8.8 as a guide, identify Semicircular canals: three loops of bony SPECIAL SENSES SPECIAL THE NERVOUS NERVOUS THE

the following parts of the middle ear: labyrinth that contain sensory recep- AND SYSTEM Malleus: the first and largest ossicle, it tors, which are activated by body connects the inner surface of the movement. They transmit nerve tympanic membrane to the second impulses to the brain for the interpre- ossicle. tation of equilibrium. The receptors Incus: the middle ossicle, which contacts are located within expanded areas the malleus to transmit vibrations at the base of the loops known as from it to the third ossicle. ampullae. Stapes: the third ossicle, which articulates Vestibule: a small chamber between the with the incus. Its distal end forms cochlea and semicircular canals. It a flattened disc, which fits over an contains the utricle and saccule, ocal opening in the lateral wall of the which house receptors sensitive to tympanic cavity called the fenestra movements of the head. vestibuli (oval window). A round opening, called the fenestra cochlea (round window), is located slightly below the oval window. 140 Chapter Eight

Squamous part of temporal bone

Mastoid part of temporal bone

Petrous part of temporal bone Internal auditory meatus

Tympanic part of temporal bone (tympanic bulla)

Dissection of Temporal Bone

Malleus Incus

Tympanic membrane Stapes

The Middle Ear

Fenestra vestibuli Ampulla

Semicircular canals Cochlea

Vestibule

The Bony Labyrinth

Figure 8.8 – Ear structures. © bluedoor, LLC

www.eig.net

Figure 8.8 OUTERNET Publishing The Nervous System and Special Senses 141 Chapter Review A. Answer the following multiple-choice questions by circling the most correct answer.

1. The brain and spinal cord are organs within the a. cranial cavity b. peripheral nervous system c. central nervous system d. csf

2. The dura mater is the outermost of the a. layers of the brain b. meninges c. spinal cord regions d. cerebrum

3. The convoluted mass that forms most of the forebrain is the a. cerebrum b. cerebellum c. thalamus d. hypothalamus

4. The small component of the diencephalon that manages involuntary actions is the a. thalamus b. hypothalamus c. pons d. cerebral cortex

5. A thick, transverse band of white matter connecting the two cerebral hemispheres is called the a. corpus callosum b. longitudinal fissure c. central sulcus d. cerebellum

6. The tectum and cerebral peduncles are parts of the

a. forebrain b. hindbrain SENSES SPECIAL THE NERVOUS NERVOUS THE c. midbrain d. cerebrum AND SYSTEM

7. The vermis, folia, and arbor vitae may be found within the a. cerebellum b. cerebrum c. forebrain d. midbrain

8. The H-shaped mass of tissue in the center of the spinal cord is a. white matter b. gray matter c. covered by meninges d. continuous with the cerebral cortex

9. The femoral nerve arises from the: a. lumbosacral plexus b. cervical plexus c. dorsal rami d. brachial plexus

10. Photoreceptors, called rods and cones, may be found within the a. labyrinth b. retina c. anterior chamber of the eye d. tympanic cavity 142 Chapter Eight

B. Complete the sentences below by providing the missing terms from the chapter material.

1. The efferent nervous system includes the ______, which routes impulses to smooth muscles and glands.

2. In order to remove the brain from the cranial cavity, you severed the ______, which were attached to the brain stem at 12 different sites on each side of the brain.

3. The primary functional zone of the cerebrum is the outer fringe of gray matter, known as the ______.

4. The midbrain, pons varolii, and medulla oblongata together form the ______.

5. The spinal cord terminates as a slender filament, called the ______, in the base of the tail.

6. The plexus that is located medial to the shoulder and cranial to the 1st rib, and can be observed from the ventral side deep to the pectoral muscles, is the ______.

7. A vertical row of autonomic ganglia extending along both sides of the vertebral column from the base of the skull to the tail describes the ______.

8. Taste receptors are organized into specialized groups of cells, known as the ______.

9. The large oval or spherical structure that is suspended by suspensory ligaments extending from the ciliary body and located behind the pupil is called the ______.

10. The ______is a coiled, snail-shell-like part of the labyrinth that contains the receptors responsible for audation, known as hair cells.

C. Answer the following descriptive and critical-thinking questions with a brief explanation in the spaces provided.

1. Describe the role of the cerebrum in achieving the functions of the nervous system.______

______

______

______

______

______The Nervous System and Special Senses 143

2. Identify the structures that light must pass through in order to stimulate photoreceptors.

______

______

______

______

______

______

3. Describe the pathway of vibrations that result in audation. ______

______

______

______

______

______SPECIAL SENSES SPECIAL THE NERVOUS NERVOUS THE SYSTEM AND AND SYSTEM ______

145

chapter nine THE

The endocrine system works in hand with the nervous system to regulate body functions. Like the nervous system, it provides a method of control in order to keep the body functioning, despite changing conditions in the environment. Thus, the primary role of the endocrine system is to achieve homeostasis, a state in which the body’s equilibrium is maintained. The endocrine system communicates to the body by secreting chemicals into the bloodstream. The chemicals are called hormones, which are produced by special organs known as endocrine glands. The organs are also called glands because their primary function is the secretion of a product. Endocrine glands secrete hormones directly into the watery environment surrounding each cell. From there, the hormones enter the bloodstream, which carries them throughout the body’s circula- tion until they reach the part of the body they are to affect. Because blood flows much more slowly than the conduction of a nerve impulse, a hormone takes longer to reach its destination. As a result, the control provided by the endocrine system occurs more slowly, and also lasts longer, when com- pared to the nervous system. Structurally, the endocrine system consists of the organs of the body that secrete hormones, which are scattered throughout the body. They include seven primary organs: pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, and gonads. Several other organs also secrete hormones, although as a secondary function. You have studied them in previous chapters so they will not be considered here; they include the stomach, kidneys, thymus, and heart. ENDOCRINE THE SYSTEM

Pituitary Gland Pineal Gland

The pituitary gland, which is also called the Similar to the pituitary, the pineal gland is hypophysis, is connected to the hypothalamus at located within the cranial cavity. It forms part the base of the brain (Figure 9.1). The narrow of the diencephalon, which you identified in bridge between the pituitary gland and the hypo- Chapter 8 (Figure 9.1).www.eig.net It is a small gland, which thalamus is known as the infundibulum. You produces a hormoneFigure () 6.6 that regulates have identified the pituitary gland during your biological cycles. If OUTERNETthe brain Publishing of your cat is still study of the nervous system (Chapter 8), so you available to observe, identify the pineal gland as need not observe it again in your cat. The pitu- the small caudal projection between the cerebral itary gland is a small oval gland composed of two hemispheres. parts: the (adenohypophysis) and the (neurohypophysis). It secretes a number of hormones, which are listed in Table 9.1. 146 Chapter Nine

Thyroid Gland Pancreas

The thyroid gland is located caudal to the larynx You have observed the pancreas in Chapter 4, in the ventral neck region (Figure 9.1). It consists because it performs digestive functions. Recall of two lobes, right and left, that are often con- that it is an oblong, glandular structure located nected near the ventral midline by a thin bridge dorsal to the stomach in the abdominal cavity of fragile tissue called the isthmus. The thyroid (Figure 9.1). The endocrine functions of the gland secretes thyroxin, a hormone that regulates pancreas are isolated within small clusters of cells the rate of cellular metabolism in all body cells. surrounded by -secreting cells. It also secretes , which reduces The clusters are known as islets of Langerhans. levels in the bloodstream. Identify the thyroid The cells of the islets secrete and gluca- gland in the neck of your specimen. gon, which regulate glucose (sugar) levels in the bloodstream. Identify the pancreas once again Parathyroid Glands where it lies within the abdominal cavity. The parathyroid glands are four, or sometimes Gonads five, small bodies embedded within the dorsal side of the thyroid gland (Figure 9.1). Because of The gonads are the testes in the male and the their small size, they are not evident during rou- ovaries in the female. You have identified these tine dissection. The parathyroid glands secrete sexual organs in your study of Chapter 7. They , which increases calcium are organs of the endocrine system because their levels in the bloodstream and is an antagonist to primary function is the secretion of hormones. calcitonin. Recall that the male testes secrete testosterone, and the female ovaries secrete estrogen and pro- Adrenal Glands gesteron. Identify these endocrine glands in a male and a female cat once again (Figure 9.1). The adrenal glands are a pair of oval organs, each located ventromedial to a kidney (Figure 9.1). Also known as the suprarenal glands, each con- sists of an outer that secretes ste- roid hormones and an inner that secretes epinephrine and . The steroid hormones of the adrenal cortex regulate water balance, reduce , participate in , and stimulate sex characteristics and sex cell development. The medullary products supplement the effect of the sympathetic division of the . Identify the adrenal glands in your speci- men. The human adrenals actually cap the superior border of the kidneys. The Endocrine System 147

Pineal gland

Pituitary gland

Thyroid gland

Parathyroid glands Thymus gland

Heart

Adrenal gland Kidney

Pancreas

Ovary

Testes THE ENDOCRINE ENDOCRINE THE SYSTEM © bluedoor, LLC Figure 9.1 – Endocrine glands of the cat.

www.eig.net

Figure 9.1 OUTERNET Publishing 148 Chapter Nine

GLAND HORMONE SECRETED PRIMARY EFFECT

Pituitary Gland: Anterior Lobe (GH) Controls growth and development -stimulating hormone (MSH) Stimulates to increase skin pigmentation (PRL) Stimulates milk secretion by the mammary glands Adrenocorticotropic hormone (ACTH) Stimulates the cortex of the adrenal glands Thyroid-stimulating hormone (TSH) Stimulates the thyroid gland Follicle-stimulating hormone (FSH) Stimulates development of ove, sperm (LH) Stimulates the secretion of sex hormones by the gonads

Oxytocin (OT) Stimulates contractions of the uterus and the release of milk by mammary glands Posterior Lobe Antidiuretic hormone (ADH) Stimulates water reabsorption in the kidneys

Pineal Gland Melatonin Regulates body rhythms

Thyroid Gland Thyroxin (T4) and Triiodothyronin (T3) Controls catabolic metabolism and protein synthesis in most body cells Calcitonin (CT) Reduces calcium levels in the blood

Adrenal Glands: Medulla Epinephrine & Norepinephrine Prolongs the conditions responsible for the “flight or fight” response

Cortex Mineralocorticoids () Maintains fluid balance by stimu- lating the retention of sodium and excreting potassium; helps regulate blood pressure

Glucocorticoids (, corticosterone, Stimulates glycogen formation and ) storage, increases body resistance to stress, and reduces inflammation

Sex hormones (androgens & ) Stimulates sex characteristics; stimu- lates sex cell development Pancreas (Islets of Langerhans) Glucagon Stimulates the conversion of glycogen to glucose

Insulin Stimulates the conversion of glucose to glycogen

Gonads: Ovaries Estrogens Stimulates development of female sex characteristics, ovarian cycle, and menstrual cycle

Testes Testosterone Stimulates development of male sex characteristics, and sperm production

Table 9.1 – Endocrine glands and their hormones The Endocrine System 149 Chapter Review

A. Answer the following multiple-choice questions by circling the most correct answer.

1. The chemical messengers of the endocrine system are known as a. b. c. hormones d. endoglastins

2. The pituitary gland has a direct connection to the a. cerebral cortex b. hypothalamus c. thalamus d. pineal gland

3. The pineal gland is located within the a. cranial cavity b. diencephalon c. brain d. all of the above

4. The endocrine gland that is located below the larynx in the ventral neck region is the a. thalamus b. c. thyroid gland d. pituitary gland

5. The four or five tiny glands that are embedded within the thyroid gland are known as a. lymph nodes b. parathyroid glands c. tumors d. pineal glands

6. The glands that may be found ventromedial to each kidney are the a. adrenal glands b. gastric glands c. islets of Langerhans d. parathyroid glands

7. The islets of Langerhans are clusters of endocrine cells located within the ENDOCRINE THE a. hypothalamus b. ventral neck region c. pancreas d. gonads SYSTEM

8. The gonads are endocrine glands because they a. produce the gametes b. serve reproductive functions c. secrete hormones d. none of the above

9. Calcium levels in the blood are regulated by the thyroid and a. metabolic activity b. parathryoid glands c. bone cells d. adrenal glands

10. Insulin and glucagon are hormones that regulate sugar levels in the blood. They are secreted by endocrine cells within the a. pancreas b. adrenal cortex c. thyroid gland d. anterior pituitary gland 150 Chapter Nine

B. Complete the sentences below by providing the missing terms from the chapter material.

1. Structurally, the endocrine system consists of the organs of the body that secrete ______.

2. The ______is connected to the hypothalamus at the base of the brain.

3. The ______is part of the diencephalon of the brain.

4. The ______is located on the ventral aspect of the neck.

5. The ______are tiny glands that are embedded within the thyroid gland.

6. The ______are located ventromedial to each kidney.

7. The ______contains clusters of endocrine cells known as islets of Langerhans.

8. The glands that secrete testosterone are the ______.

9. Estrogens are secreted by the ______.

10. The anterior ______regulates several other endocrine glands.

C. Answer the following descriptive and critical-thinking questions with a brief explanation in the spaces provided.

1. Contrast the primary functional role of the nervous system with that of the endocrine system.

______

______

______

______

______

______151

Appendix ANSWERS TO CHAPTER REVIEWS

Chapter One Chapter Two

A. 1. d; 2. a; 3. a; 4. c; 5. b; 6. b; 7. d; 8. c; A. 1. c; 2. d; 3. c; 4. d; 5. d; 6. c; 7. b; 8. b; 9. c; 10. a 9. c; 10. a B. 1. mastoid process; 2. occipital; 3. sphenoid; B. 1. blunt probe; 2. needle probes; 3. eyelids; 4. palatine; 5. maxillary; 6. coronal suture; 4. pectoral; 5. urogenital; 6. axilla; 7. ; 7. thoracic; 8. ; 9. ilium, ischium; 8. cutaneus maximus; 9. platysma; 10. single 10. talus piece C. 1. The talus is very large, the calcaneus is C. 1. The skin should be retained so that it elongate, the metatarsals are elongate, may be used as a wrap between dissec- and the phalanges are angled to support tions to reduce dehydration of tissues. weight. 2. Over-use of a scalpel can lead to 2. Overall, the human cranium is much unnecessary cuts and a greater chance of larger to accommodate the larger brain. per-sonal during a dissection. More subtle differences include no dis- 3. Dissection provides experience with tinct presphenoid in the human, and touching and seeing real structures, the temporal bone has less which enhances learning and recall. It distinctive divisions in the human. also serves to teach dissection skills. 3. The innominate bones of the human differ from the cat due to the posture dif- Chapter Three ferences of bipedal gait. The innominate bones are in a more upright position in A. 1. a; 2. b; 3. b; 4. b; 5. c; 6. c; 7. b; 8. a; the human, and the ilium has a greater 9. b; 10. a APPENDIX width relative to overall size. Also, the B. 1. ; 2. fascia; 3. adduction; innominate bones are sexually dimor- 4. pectoantebrachialis; 5. ; phic in humans; that is, the female ilium 6. brachialis; 7. brachioradialis; 8. fascia lata; flares laterally, while the male ilium is 9. biceps femoris;www.eig.net 10. serratus ventralis more upright, and the angle between the C. 1. The quadricepsFigure 6.6 femoris group primar- OUTERNET Publishing opposing pubic bones is more obtuse in ily extends the shank at the knee . the female to form the birth canal. The four muscles provide great force to enable the quadriped to run and leap by the push downward force that is exerted onto the ground. This force must be even greater in bipeds, because there is no assistance in the action by the fore- limbs. 152 Appendix

2. In humans, the gluteus maximus is a Chapter Five much more extensive muscle than the gluteus maximus of quadripeds due to A. 1. a; 2. b; 3. b; 4. c; 5. b; 6. d; 7. c; 8. b; the stepping motion required of the 9. c; 10. b bipedal gait. The g. medius is larger B. 1. external respiration; 2. diaphragm; 3. tho- than the g. maximus in the cat and other racic; 4. primary bronchi; 5. nasal chambers; quadripeds, but smaller that the g. maxi- 6. thyroid cartilage; 7. glottis; 8. alveoli; mus in humans. 9. pleural; 10. apex 3. The human biceps brachii includes two C. 1. Respiration includes ventilation, which heads of origin, from which its name is is composed of inspiration (inhaling) derived: a short head at the glenoid fossa and expiration (exhaling). Inspiration and a long head at the coracoid process. is initiated when respiratory muscles The biceps brachii of the cat has only one contract, and expiration results when the origin: the glenoid fossa. In both organ- muscles relax. External respiration is gas isms, the action is the same. exchange between alveoli and capillaries due to pressure differences, resulting in Chapter Four oxygen moving into the bloodstream. Internal respiration is the movement of A. 1. a; 2. c; 3. c; 4. a; 5. d; 6. c; 7. b; 8. b; 9. oxygen molecules from the bloodstream a; 10. b to body tissues. B. 1. accessory organs; 2. parietal peritoneum; 2. The lungs are composed of tiny air sacs 3. abdominal cavity; 4. mandibular glands; (alveoli), their surrounding capillaries, 5. hard palate; 6. tongue; 7. oropharynx; larger blood vessels, and the bronchial 8. mesentery; 9. gallbladder; 10. ileocecal tree. The bronchial tree begins when the C. 1. The oral cavity tears and chews food primary bronchi divide into secondary (mastication); salivary glands secrete bronchi within each , then d i v i d e saliva, which begins carbohydrate diges- again into tertiary bronchi. The tertiary tion and lubricates food for ; bronchi eventually divide to form bron- stomach begins protein digestion; and chioles, which end in alveolar ducts that small intestine finalizes chemical diges- contain alveoli. tion and performs nutrient absorption. 2. The liver secretes bile to assist in fat Chapter Six digestion within the small intestine; the gallbladder provides temporary storage A. 1. a; 2. b; 3. c; 4. c; 5. b; 6. b; 7. b; 8. c; of bile; pancreas secretes a collection of 9. b; 10. c enzymes that participate in chemical B. 1. capillaries; 2. left ventricle; 3. right atrium; digestion within the small intestine. 4. brachiocephalic artery; 5. caudal vena 3. Based on the strict carnivorous diet cava; 6. ventricles; 7. external jugular veins; of cats and the close similarity of GI 8. radial artery; 9. celiac trunk; 10. hepatic tract anatomy between cats and humans, portal circulation it may be suggested that humans are C. 1. Right atrium through tricuspid valve to pri-marily carnivores. The dentition of right ventricle, through pulmonary valve humans, however, indicates an adapta- to pulmonary trunk and pulmonary cir- tion to chewing and grinding plant mate- cuit, pulmonary veins to left atrium, rial, suggesting that meat consumption through bicuspid valve to left ventricle, is supplemented with plants, providing through aortic valve to . evidence that human adaptations point 2. A portal system shunts blood from one to an omnivorous diet. network to another, whereas a Appendix 153

normal venous system carries blood from Chapter Eight a capillary network toward the heart. The hepatic portal circuit shunts blood A. 1. c; 2. b; 3. a; 4. b; 5. a; 6. c; 7. a; 8. b; 9. from the digestive tract to the liver for a; 10. b processing before it enters the general B. 1. autonomic system; 2. cranial nerves; circulation. 3. cerebral cortex; 4. brain stem; 5. filum 3. The aortic branches are, from proximal terminale; 6. brachial plexus; 7. sympa- to distal, the brachiocephalic artery, left thetic trunk ganglia; 8. taste buds; 9. lens; subclavian artery, celiac trunk, superior 10. cochlea mesenteric artery, adrenolumbar arteries, C. 1. The cerebrum consists of the cerebral renal arteries, gonadal arteries, caudal cortex, which receives sensory informa- mesenteric artery, lumbar arteries, deep tion, processes it by interpretation and circumflex iliac arteries, external iliac correlation with memory, and initiates artery, motor responses in order to maintain homeostasis. It also manages conscious- Chapter Seven ness. 2. Light passes through the conjunctiva, A. 1. b; 2. a; 3. b; 4. b; 5. a; 6. b; 7. c; 8. b; then the anterior cavity with aqueous 9. c; 10. b humor, then the pupil, then the lens, B. 1. nephrons; 2. renal pelvis; 3. trigone; then the posterior cavity with aque- 4. urethra; 5. scrotum; 6. seminiferous ous humor, then the choroid, then the tubules; 7. vas deferens; 8. ovarian ligament; retina to stimulate rod and cone cells 9. uterine horns; 10. urogenital aperture embedded within the retina. C. 1. The nephrons are located in the renal cor- 3. A mechanical vibration is collected by tex and extend into the renal medulla the pinna (auricle) and directed into the of a kidney. They filter blood, reab- external auditory meatus to contact the sorb water from the filtrate, and secrete tympanic membrane, which vibrates in excess ions in the formation of urine. response. This vibration is transmitted Urine formation helps manage blood to the ossicles: malleus, incus, and sta- pressure, fluid and salt balance in body pes, then to the oval window and into fluids, and eliminates metabolic the cochlea. The vibration forms waves waste materials. in fluid, which passes over hair cells to 2. Spermatozoa are produced within stimulate the impulse. seminiferous tubules of the testes, then

pass into the ductus epididymus, then Chapter Nine APPENDIX into the vas deferens, then into the ejacu- latory duct of the urethra. The urethra A. 1. c; 2. b; 3. d; 4. c; 5. b; 6. a; 7. c; 8. c; opens to the exterior via the urogenital 9. b; 10. a orifice. B. 1. hormones; 2. pituitary gland; 3. pineal 3. The human vulva contains two pairs of gland; 4. thyroid gland; 5. parathyroid labia, majora and minora, rather than glands; 6. adrenal glands; 7. pancreas; a single pair as seen in the cat. Also, 8. testes; 9. ovaries; 10. pituitary gland the human clitoris is a more prominent structure. Finally, the urethra and vagi- na enter the vulva as separate openings in human females: as the urethral orifice and the vaginal orifice. 154 Appendix

C. The nervous system relies upon nerve impulses to convey information from one part of the body to another. The nerve impulses move very rapidly, bring- ing about change in an instant. In con- trast, the endocrine system relies upon the secretion of hormones, their move- ment into the bloodstream, and the delivery of hormones by way of blood flow. Consequently, hormone action to maintain homeostasis is much slower, and tends to last longer, than nervous action. 155

Appendix DISSECTION PHOTOS

Pectoralis major m. m.

Super cial pectoral m. Xihumeralis m.

Serratus ventralis m. Tensor fascia antebrachii

Latissimus dorsi m.

Figure 1 – Muscles of chest and shoulder, superficial lateral view, cat DISSECTION

www.eig.net PHOTOS

Figure 6.6 OUTERNET Publishing 156 Appendix B

Serratus ventralis m.

Rectus abdominus m.

Figure 2 – Muscles of , deep, ventral view, cat

Latissimus dorsi m. Supraspinatus m. (re ected)

Acromiotrapezius m. Infraspinatus m. Lavator scapulae ventralis m. Teres major m.

Triceps brachii lateralis m. Serratus ventralis m.

Triceps brachii longus m.

Figure 3 – Muscles of upper back, shoulder, and thorax, lateral view, cat Appendix B 157

Pectoantebrachialis m.

Xiphihumeralis m.

Pectoralis major m. Pectoralis minor m.

Serratus ventralis m. Tensor fascia antebrachii

Latissimus dorsi m. (re ected)

Figure 4 – Muscles of thorax, lateral view, cat DISSECTION PHOTOS 158 Appendix B

Tensor fascia antebrachii (re ected)

Biceps brachii m.

Supercial pectoral m. Triceps brachii longus m.

Pectoralis major m.

Latissimus dorsi m. Pectoralis minor m. (re ected)

Figure 5 – Muscles of shoulder and brachium, deep, ventral view, cat Appendix B 159

External oblique m. Linea alba

External oblique m.

Transversus abdominis m.

Internal oblique m.

Rectus abdominis m.

Figure 6 – Muscles of abdominal wall, ventral view, cat

Linea alba

Rectus abdominis m.

Transversus abdominis m.

Internal oblique m. (re ected) DISSECTION

External oblique m. PHOTOS (re ected)

Figure 7 – Muscles of abdomen, ventrolateral view, cat 160 Appendix B

Flexor carpi radialis m.

Palmaris longus m.

Extensor carpi radialis m.

Flexor carpi ulnaris m.

Pronator teres m.

Figure 8 – Forelimbs muscles, medial view, cat Appendix B 161

Flexor carpi radialis m.

Palmaris longus m.

Extensor carpi radialis longus m.

Brachioradialis m.

Flexor carpi ulnaris m. Pronator teres m. DISSECTION PHOTOS

Figure 9 – Muscles of antebrachium, medial view, cat 162 Appendix B

Gluteus maximus m. Caudofemoralis m. (re ected) Gluteus medius m. Biceps femoris m. (re ected) Tensor fasciae latae m.

Gastrocnemius m. Sciatic n. lateral head

Peroneus m. Sartorius m. Long digital extensor m. Common peroneal n. Tibialis anterior m.

Figure 10 – Muscles of hindlimb, lateral view, cat Appendix B 163

Rectus femoris m.

Vastus lateralis m. Adductor longus m.

Adductor femoris m. Vastus medialis m.

Gracilis m. Semimembranosus m. (re ected)

Plantaris m. Long digital exor m. Gastrocnemius m.

Tibialis anterior m.

Figure 11 – Muscles of hindlimb, medial view, cat DISSECTION PHOTOS 164 Appendix B

Pectineus m. Sartorius m.

Vastus lateralis m.

Adductor longus m. Rectus femoris m.

Adductor femoris m.

Vastus medialis m.

Semimembranosus m. Gracilis m.

Figure 12 – Muscles of thigh, deep, medial view, cat

Common carotid a. Radial a. & v.

External jugular v. Ulnar a. & v. Subclavian a.

Axillary a. Brachial a.

Brachial v. Axillary v.

Figure 13 – Blood vessels of forelimb, cat Appendix B 165

Larynx Right common carotid a. Left common carotid a.

Trachea Left subclavian v.

Left brachiocephalic v. Axillary a.

Left subclavian a. Right subclavian a.

Brachiocephalic a. Cranial vena cava

Left lung Heart

Figure 14 – Blood vessels cranial to heart, cat DISSECTION PHOTOS 166 Appendix B

Trachea

Heart

Left lung

Gallbladder Diaphragm Liver

Stomach

Spleen

Intestine

Colon

Urinary bladder

Figure 15 – Internal organs of cat Appendix B 167

Trachea

Left common carotid a. Right common carotid a.

Right subclavian a. Left subclavian a.

Cranial vena cava Brachiocephalic a. Right lung, cranial lobe Left lung, Auricle of cranial lobe right atrium

Heart Right lung, middle lobe

Left lung, Right lung, middle lobe accessory lobe

Diaphragm Left lung, caudal lobe

Figure 16 – Organs of thoracic cavity, cat DISSECTION PHOTOS 168 Appendix B

Right common carotid a. Right external jugular v. Left common carotid a. Right subclavian a. Right subclavian v.

Left subclavian a. Brachiocephalic v. Brachiocephalic a. Aortic arch Intercostal aa. Left lung

Descending thoracic aorta

Liver Esophagus

Diaphragm

Spleen

Left kidney

Figure 17 – Descending thoracic aorta, lateral view, cat Appendix B 169

Heart Left lung

Diaphragm

Liver, quadrate lobe Liver, left medial lobe

Gallbladder

Liver, left lateral lobe

Liver, right medial lobe Stomach

Spleen

Intestine

Urinary bladder DISSECTION PHOTOS

Figure 18 – Abdominopelvic cavity, superficial structures, cat 170 Appendix B

Left kidney Caudal vena cava

Left renal v.

Descending colon

Left ureter Intestine

Left iliolumbar a. & v.

Rectum Left common iliac v.

Urinary bladder

Left external iliac a. & v.

Left femoral a. & v.

Figure 19 – Abdominopelvic cavity, deep structures, cat Appendix B 171

Left ureter

Urinary bladder

Urethra

Prostate gland

Right vas deferens Left vas deferens Bulbourethral gland

Penis

Epididymis Glans penis

Testis DISSECTION PHOTOS

Figure 20 – Male reproductive system, cat

173

Appendix GLOSSARY

A Adrenal medulla: The inner region of the adre- nal glands, which secretes epinephrine and Abdomen (AB-do-men): The regional area norepinephrine. between the diaphragm and pelvis. (ad’-ven-TISH-ya): The outermost Abdominal cavity: The membrane-bound space covering of an organ or tissue. between the diaphragm, abdominal wall, and Alimentary canal (a’-li-MEN-ta-re ca-NAL): The pelvis. tube of the digestive system that includes the Abdominopelvic (ab-do’-mi-no-PEL-vik) cavity: mouth, esophagus, stomach, small intestine, The membrane-bound space that includes and large intestine. Also called the digestive the abdominal cavity and pelvic cavity. tract, and gastrointestinal (GI) tract. Abduction (ab-DUK-shun): Movement away Alveolar (al-VE-o-lar) duct: A branch of a respi- from the midline. ratory within the lungs that leads Absorption (ab-SORB-shun): The passage of to alveoli and alveolar sacs. digested foods from the digestive tract and Alveolar sac: Two or more alveoli that share a into the bloodstream. common opening from an . Acetabulum (a’-se-TAB-yoo-lum): A cup-shaped Alveolus (al-VE-o-lus): alveoli plural form: A depression on the lateral surface of the coxal microscopic air sac within the lungs. (hip) bone. It receives the head of the Amylase (AM-i-las): An enzyme produced by to form the hip joint. the salivary glands and pancreas that cleaves Achilles (a-KIL-es) : Also called the cal- starch, glycogen, and other polysaccharides caneous tendon, it is the common tendon during chemical digestion. of the calf muscles that originates from the Anatomical (a-na-TOM-ik-al) position: The ref- calcaneus (). erence position, in which the bipedal subject Adduction (ad-DUK-shun): Movement toward is standing erect with the feet facing forward, the midline. arms are at the sides, and the palms of the Adipose (AD-i-pos): A type of loose connective are facing forward (the thumbs are to tissue containing , or fat cells. the outside). www.eig.net Adrenal cortex (a-DRE-nal KOR-teks): The Anatomy (a-NA-to-me):Figure 6.6 The study of the struc- outer region of the adrenal glands, located ture of the body.OUTERNET Publishing

superior to each kidney. It secretes steroid Anterior (an-TER-e-or): Toward the belly or GLOSSARY hormones, including glucocorticoids and front of the body. In humans, it is also called mineralocorticoids. ventral. Adrenal glands: Two endocrine glands, each situ- Anterior horn: A region of the spinal cord gray ated superior to a kidney. Also called supra- matter containing the cell bodies of m o t o r renal glands. neurons. It is also called the ventral horn. 174 Glossary

Anterior root: The structure emerging from the Ascending colon (a-SEN-ding KO-lon): A seg- spinal cord on its anterior aspect that con- ment of the large intestine that extends from tains axons of motor neurons. It is also called the cecum to the transverse colon. the ventral root. Atrioventricular (a-tre-o-ven-TRIK-yoo-lar) node: Anterior pituitary gland: The portion of the A cluster of specialized cardiac (heart) cells in pituitary gland at the base of the brain com- the right atrial wall that serve as part of the posed of glandular epithelium. heart conduction system. Anus (A-nus): The distal end and outlet of the Atrioventricular (AV) valve: Two of four heart rectum. valves, each of which is located between an Aorta (a-OR-ta): The main trunk of the systemic atrium and a ventricle. The right AV valve circulatory circuit. It originates from the left is also called the tricuspid valve, and the left ventricle of the heart. AV valve is also called the bicuspid or mitral Aortic semilunar valve: One of four heart valves, valve. it consists of three cusps that are attached to Atrium (A-tre-um): One of two superior cham- the wall of the aorta near its origin from the bers of the heart. Plural form is atria. left ventricle. It is also called the aortic valve. Audation (ah-DA-shun): The sense of hearing. Apex (A-peks): The extremity of a conical or Auditory ossicles (AH-di-tor-e OS-ik-elz): The pyramidal structure. The apex of the heart is three small bones within the middle ear that the rounded, inferior-most tip that points to transmit sound vibrations: the malleus, incus, the left side. and stapes. Aponeurosis (ap’-o-noo-RO-sis): A broad, sheet- Autonomic ganglion (ah’-to-NOM-ik GANG- like tendon joining one muscle with another le-on): A cluster of cell bodies that lie or with a bone. outside the central nervous system, serving Appendicular (ap’-en-DIK-yoo-lar): Pertaining either the sympathetic or parasympathetic to the major appendages, the forelimbs and divisions. hindlimbs. Autonomic nervous system (ANS): A division Aqueous humor (AK-we-us HYOO-mor): The of the peripheral nervous system that serves watery fluid that fills the anterior compart- body functions not requiring conscious con- ment of the eye. trol. It is divided into sympathetic and para- Arachnoid (a-RAK-noyd): The middle of three sympathetic subdivisions. connective tissue coverings (meninges) of the Axilla (ak-SIL-a): The small depression beneath brain and spinal cord. the arm where it joins the trunk of the body. Areolar (a-RE-o-lar): A type of connective tissue It is also called the armpit. with sparse protein fibers in the (loose Axial (AK-se-al): The body region along the connective tissue). midline, which includes the head, neck, and Arrector pili (a-REK-tor Pi-le): Smooth muscle trunk. fibers attached to hair within the skin. Axon (AK-son): A long process of a neuron that Arteriole (ar-TE-re-ol): A small tributary from a carries a nerve impulse away from the cell larger artery that delivers blood to a capillary. body. Artery (AR-ter-e): A that carries blood away from the heart. B Articular cartilage (ar-TI-kyoo-lar KAR-ti-lej): The cartilage that covers the end of a bone : A thin layer of extracellu- where it forms a joint with another bone. lar material that underlies epithelium. Articulation (ar-tik’-yoo-LA-shun): A synonym Basilar (BAS-i-lar) membrane: One of two mem- for joint, which is a point of contact between branes in the inner ear that form the cochlear two opposing bones. duct. It supports the organ of Corti. GLOSSARY 175 three types of . It is characterized by three types of joints. It is characterized oppos- the presence of cartilage that connects ing bones. end of spinal nerves and roots at the inferior of the spinal cord. intestine that receives the ileum of the small intestine. isms. the nucleus and much of the cytoplasm. Also called the soma. the center of the macula lutea of the retina. It contains cone cells (only), and is the area of optimal visual acuity (clearest vision). (of the foot), it forms the heel. it forms the (of the foot), Plural form is calyces. pelvis (of the kidney). bone tissue that connects nel within compact is canaliculi. lacunae. Plural form arterioles with vessel that interconnects is a single cell wall capillary The venules. and is the only site of layer in thickness, between the bloodstream nutrient and body cells. by characterized is It tissue. muscle of and striations and involuntary contractions, makes up the bulk of the heart wall. the wrist of the wrist. As a group, the bones of are referred to as the carpus. con- characterized by the presence of a matrix and taining a dense distribution of proteins matrix is a thickened . The secreted by . Cauda equina (KAH-da e-KWI-na): The group large end of the proximal Cecum (SE-kum): The Cell: The basic living unit of multicellular organ- Cell body: The portion of a neuron that contains Central fovea (FO-ve-a): A small depression in C tarsal bone A large (kal-KA-ne-us): Calcaneous of the renal A cuplike extension Calyx (KAL-iks): A small chan- Canaliculus (kan’-a-LIK-yoo-lus): A microscopic blood Capillary (KAP-i-lar’-e): Cardiac (KAR-de-ak) muscle: One of three types bones Carpals (KAR-palz): The eight individual Cartilage (KAR-ti-lej): A type of connective tissue of One (kar’-ti-LA’-jin-us) joint: Cartilaginous dulla

ructures ructures me st

(BUK-al): Pertaining to the mouth or the mouth or to the (BUK-al): Pertaining cheeks. reproductive male the in glands pair of small system located inferior to the prostate gland. Its secretions contribute to semen. Also called Cowper’s glands. trachea and the . Plural form is bronchi. oblongata. consists the respiratory conduction zone that the tra- of a series of tubes that branch from to chea (the primary bronchi), and continue second- branch after entering each lung (into ary and tertiary bronchi). as branches from tertiary arise tubes that bronchi within each lung. passageways that carry air between the the gallbladder. It assists in the digestion of in the digestion of It assists the gallbladder. intestine. fats within the small present, due to the exit toreceptive cells are nerve. point of the optic and contains lined by a membrane, including organs. ear that consists of cavities tion of the inner bone, forming the vesti- within the temporal bule, cochlea, and semicircular canals. arm. rami of work of nerves from the anterior T1. The spinal nerves C5, C6, C7, C8, and the fore- nerves of the brachial plexus supply limbs. consists of the midbrain, pons, and tricular (AV) valve of the heart. It is also heart. It is also valve of the tricular (AV) mitral valve. called the Buccal Bulbourethral (bul’-bo-yoo-RE-thral) glands: A Bronchial tree (BRONG-ke-al): A portion of Bronchiole (BRONG-ke-ol): A series of small (BRONG-kus): Any one of the air : A fluid secreted by the liver and stored in liver and stored in secreted by the Bile: A fluid pho- where no of the retina Blind spot: A region that is internally Body cavity: A space in the body The por- Bony labyrinth (BO-ne LAB-e-rinth): upper Brachial (BRA-ke-al): Pertaining to the - Brachial plexus (BRA-ke-al PLEK-sus): A net that brain of the inferior portion Brain stem: The - left atrioven valve : The (bi-KUS-pid) Bicuspid Glossary 176 Glossary

Central nervous system (CNS): A major division Chromosome (KRO-mo-som): One of the of the nervous system that contains the brain structures (46 in human cells) within the and spinal cord. that contains genetic material. Cephalic (se-FAL-ik): Pertaining to the head Chromosomes become visible during cell region. division. Cerebellum (ser’-e-BEL-um): A functional region Ciliary body (SIL-e-ar-e BOD-e): Part of the of the hindbrain located inferior to the cere- vascular tunic of the eyeball, along with the brum. It coordinates muscle movement. choroid and iris. It suspends the lens, and Cerebral aqueduct (SER-e-bral AK-we-dukt): consists of the ciliary muscle and ligaments. A channel through the midbrain containing Cilia (SIL-e-a): A hair-like process associated with cerebrospinal fluid. It connects the third and a cell that is a modification of the plasma fourth ventricles of the brain. membrane. Its movement generates a flow Cerebral cortex: The outer layer of the cerebrum, of fluid (usually ) in the extracellular which is composed of gray matter. environment. Singular form is cilium. Cerebrospinal fluid (se-re’-bro-SPI-nal FLOO-id) Circumduction (ser’-kum-DUK-shun): A move- (CSF): A clear fluid produced as a filtrate ment at a such that the distal from blood in the choroid plexuses of the end of the bone draws a circular path. brain. It circulates through the ventricles of (KLA-vik-el): One of two bones con- the brain, the central canal of the spinal cord, necting the sternum and the forelimb. Also and the subarachnoid space of the brain and called the collarbone. spinal cord. Clitoris (KLI-tor-is): The female erectile organ Cerebrum (SER-e-brum): The largest functional located at the anterior junction of the labia region of the brain, it is the convoluted mass minora. that lies superior to all other parts of the Coccyx (KOK-siks): The fused bones at the end brain. It is the main site of integration of of the vertebral column of the human. sensory and motor impulses. Cochlea (KOK-le-a): The portion of the inner Cervical (SER-vi-kal): Pertaining to the neck ear that contains the receptors of hearing (the region. organ of Corti). Cervical plexus (PLEK-sus): A branching net- (KOL-a-jen): A protein that is an abun- work of nerves originating from the anterior dant component of connective tissue. rami of the first four cervical nerves. Colon (KO-lon): The division of the large intes- Cervix (SER-viks): The narrow, constricted part tine containing the ascending, transverse, of the uterus that lies between the vagina and descending, and sigmoid sections. the body of the uterus. Common bile duct: A tube extending from the Chondrocyte (KON-dro-sit): A mature cartilage union of the common hepatic duct and the cell. cystic duct to the duodenum (of the small Chordae tendineae (KOR-de TEN-din-e-e): intestine) that transports bile. Strands of connective tissue in the heart that Compact bone: One of two types of bone tissue, anchor atrioventricular valves to papillary it is characterized by a dense matrix filled muscles. with mineral salts and collagen arranged in Choroid (KO-royd): Part of the vascular tunic of lamellae that surround a central osteonic the eyeball. It lines most of the internal sur- (Haversian) canal. Also called dense bone. face of the sclera, thereby forming the middle Conchae (KONG-ke): Scroll-like bones in the layer of the wall of the eye. facial skeleton forming the superior, middle, Choroid plexus (KO-royd PLEK-sus): A mass of and inferior shelves and meati of the nasal specialized capillaries in the ventricles of the cavity. brain, from which cerebrospinal fluid is pro- Condyle (KON-dil): A rounded process of a duced. bone. GLOSSARY 177 carries a

(de-ok’-se-ri-bo-nyoo- originate from the brain. originate cavity. that forms the cranial the skull to the common bile bile from the gallbladder duct. plasma membrane and located within the membrane, and contain- outside the nuclear ing the cellular organelles. outside the cellular organ- cytoplasm that lies elle membranes. and microtubules of network supportive of a cell. microfilaments within the cytoplasm KLE-ik A-sid) (DNA): A nucleic acid in KLE-ik A-sid) (DNA): A nucleic the that contains helix a double shape of the protein for necessary information genetic synthesis. part downward. deep to the and composed of dense, irregular connective tissue. segment of the large intestine between the transverse colon and the . muscle dividing the thoracic cavity from the abdominopelvic cavity. surface of the body. a of surface external the covering tissue tive muscle. Also called the epimysium. Also feces from the rectum through the anus. called elimination. from the cell body of a neuron that nerve impulse toward the cell body. : One of twelve pairs of nerves that of nerves pairs of twelve : One nerve Cranial portion of The skeletal (KRA-ne-um): Cranium transports A tube that (SIS-tik dukt): Cystic duct material of a cell Cytoplasm (SI-to-plazm): The thickened fluid of the Cytosol (SI-to-sol): The A complex Cytoskeleton (ci’-to-SKEL-e-ton): Depression (de-PRE-shun): Movement of a body lying skin the layer of (DER-mis): The Descending colon (de-SEN-ding KO-lon): The Diaphragm (DI-a-fram): An internal, circular : A directional term meaning away from the Deep: A directional term meaning away - connec of sheet A (FASH-e-a): Deep fascia of Defecation (def’-e-CA-shun): The discharge Dendrite (DEN-drit): A cytoplasmic extension Deoxyribonucleic acid D

terior of blood an

arteries) and its return to the right the to its return and arteries)

and posterior portions. Also called the frontal and posterior portions. Also called the plane. LA-shun): The circulatory pathway way of to the heart wall from the aorta (by coronary atrium (by way of coronary veins). which the posterior surface of the heart into coronary veins empty. band of bundle of nerve fibers forming a two cere- white matter that interconnects the bral hemispheres of the brain. within the ovary that forms from a ruptured Graafian follicle and functions as an endocrine gland by secreting female hor- mones. organ. that connects a true rib with the sternum. that form the pelvis. Also called os coxae, or innominate bones. within the skull that contains the brain. parent membrane lining the outer surface of outer surface of lining the parent membrane eye and inner surface of the the cornea of the eyelids. It is characterized by an tissue in the body. material with rela- abundance of extracellular functions in the support tively few cells, and structures. and binding of body end of the spinal cord. The tapered terminal the eye. portion of the fibrous tunic covering vertically to divide the body into that is involved in color vision and high visual and high visual in color vision that is involved acuity. Coronary circulation (KO-ro-nar-e ser’-kyoo- Coronary sinus: An expanded venous channel on Corpus callosum (KOR-pus ka-LO-sum): A (LOO-te-um): A structure Cortex (KOR-teks): The outer portion of an A band of CAR-ti-lej): Costal cartilage (KOS-tel Coxal bones (KOK-sal bonz): The two bones Cranial cavity (KRA-ne-al CAV-i-te): The cavity (kon’-junk-TE-va): A thin, trans- A thin, (kon’-junk-TE-va): Conjunctiva basic types of : One of the four Connective tissue (KO-nus med’-yoo-LAR-is): Conus medullaris transparent, anterior Cornea (KOR-ne-a): The Coronal (ko-RO-nal) plane: A plane that extends : A photoreceptor in the retina of the eye of the the retina in : A photoreceptor Cone Glossary 178 Glossary

Diaphysis (di-A-fi-sis): The shaft of a . Efferent ductules (DUK-tyoo-elz): Small coiled Diastole (di-AS-to-le): A part of the cardiac cycle tubes that transport sperm from the rete testis characterized by relaxation of the heart cham- to the epididymis. bers, during which they fill with blood. Efferent neuron (NOO-ron): A neuron that car- Diencephalon (di-en-CEF-a-lon): A region of the ries impulses away from the central nervous brain located inferior to the cerebrum. It is system. Also called motor neuron. part of the forebrain, and contains the thala- Ejaculation (e-jak’-yoo-LA-shun): The expulsion mus, hypothalamus, and pineal gland. of semen from the penis, which is accom- Digestion (di-JES-chun): The breakdown of plished by reflexive muscle contractions. food particles into units small enough to be Ejaculatory duct (e-JAK-yoo-la-to-re dukt): A absorbed. short tube that carries sperm from the ductus Digestive tract: (see Alimentary canal). deferens to the urethra. Dilate (DI-lat): To enlarge in size or expand. (e-LEK-tro-lit): A chemical that can Distal (DIS-tal): A directional term identifying separate into ions and conduct an electric a body part located further from the origin current when in a water . or point of attachment to the trunk relative Elevation (el-e-VA-shun): Movement of a body to another. part upward. : A segment of the renal Embryo (EM-bre-o): In the human, it is the tubule (of the kidney nephron) that extends developing organism during its first eight from the to the collecting duct. weeks of life following fertilization. Dorsal (DOR-sal): A directional term indicating Endocardium (en-do-KAR-de-um): The inner toward the back side, or posterior. layer of the heart wall that forms a thin, Dorsal cavity: A major body cavity containing smooth lining covering the chambers and the cranial cavity and the vertebral canal. valves. Dorsal root: The sensory branch of a spinal nerve Endochondral ossification (en-do-KON-dral os’- that connects with the spinal cord. i-fi-KA-shun): The development of bone Dorsiflexion (dor’-se-FLEK-shun): Movement of such that bone tissue forms in replacement of the foot toward the dorsal side. hyaline cartilage. Ductus deferens (DUK-tus DEF-er-enz): The Endocrine gland (EN-do-krin gland): One of tube that conducts sperm from the epdidy- two main categories of glands, in which the mis in the testes to the ejaculatory duct. Also products are secreted into the extracellular called vas deferens and seminal duct. space and transported by the bloodstream. Duodenum (doo-o-DE-num): The first segment Also called ductless glands. of the small intestine that extends from the Endocytosis (en’-do-si-TO-sis): The active pyloric valve to the jejunum. process of bulk transport of material into a Dura mater (DYOO-ra MA-ter): The outer of cell. It includes phagocytosis and pinocyto- the three meninges that surround the brain sis. and spinal cord. Endolymph (EN-do-lymf): The fluid within the membranous labyrinth of the inner ear. E Endometrium (en’-do-ME-tre-um): The inner, vascular layer of the uterus. Effector (e-FEK-tor): Any muscle or gland that Endomysium (en’-do-MI-se-um): The deepest responds to a stimulus from a motor layer of connective tissue associated with a neuron. muscle. It surrounds individual muscle fibers. (EF-er-ent ar-TE-re-ol): An Endoneurium (en’-do-NYOO-re-um): The arteriole that transports blood away from the deepest layer of connective tissue associated of a nephron (in the kidney). with a nerve. It surrounds individual nerve fibers (myelinated axons of neurons). GLOSSARY 179 : One of four One tissue: that contains spongy bone tissue. spongy bone that contains primary tissue types, it is characterized by a characterized by tissue types, it is primary - with little intercel of cells close arrangement called epithelium. lular material. Also at the proximal end of a of . Also called . blood cell. are formed. by which erythrocytes pharynx the between canal alimentary the and the stomach. tube. the foot in an outward direction. products categories of glands, in which the them to are released into ducts that transport the body surface or into body cavities. process by which materials are transported envi- out of a cell and into the extracellular ronment. external expelling air from the lungs to the called environment, or breathing out. Also exhalation. body part such that the angle between oppos- ing bones is increased; returning to original position after flexion. tube of the external ear extending from the auricle to the tympanic membrane. It passes through the hole in the temporal bone called the external auditory meatus. consists of the appendage known as the auricle, the external auditory canal, and the tympanic membrane. nose between the external environment and the nasal cavity. Also called nostrils. (e-PIF-i-sis): The end of a long bone bone of a long The end (e-PIF-i-sis): (ep’-i-THE-le-al) Epithelial (ep’-o-NIK-e-um): A narrow region narrow A (ep’-o-NIK-e-um): A synonym for red Erythrocyte (e-RITH-ro-sit): The process Erythropoiesis (e-rith’-ro-poy-E-sis): tubular segment of Esophagus (e-SOF-a-gus): A : See auditory Eustachian (yoo-STA-she-an) tube of Eversion (e-VER-zhun): Movement of the Exocrine (EK-so-krin) gland: One of two main cellular active The (ek’-so-si-TO-sis): Exocytosis of Expiration (ek’-spi-RA-shun): The process a Extension (ek-STEN-shun): Movement of canal: The epidermal-lined auditory External External ear: The outer part of the ear, which the openings of The External nares (NAR-ez): of

ribosomes ribosomes the transport

synthesis (if

(EN-zim): A protein that performs the (EN-zim): A protein role of catalyst in a chemical reaction. role of catalyst in cytoplasm characterized by a that accepts the eosin stain. the ven- roglial cell in the brain that lines tricles. Also called ependymocytes. visceral layer of the heart wall. Also called the pericardium. epi- of skin composed of stratified squamous thelium. a consists of male reproductive system that coiled tube located within the scrotum. of hyaline that consists of a leaf-shaped piece over the cartilage that forms a movable lid opening into the trachea, called the glottis. muscle, with associated tissue connective of it surrounds the whole muscle. Also called deep fascia. most layer of connective tissue associated with a nerve. It surrounds the whole nerve. fied bone visible in a section through bone that is the remnant of the epiphyseal plate. the epiphysis and diaphysis that produces lengthwise growth of a bone. are attached, called rough ER). are attached, called cavity within a bone ing the medullary and osteoclasts. and containing osteoblasts epithelium lining the inside simple squamous the heart chambers. of blood vessels and TIK-yoo-lum) (ER): A cytoplasmic organelle organelle (ER): A cytoplasmic TIK-yoo-lum) - tubules with a hol of a series of that consists It functions in low center. cellular products (smooth ER), and as a ER), and as products (smooth cellular protein for site (e’-o-SIN-o-fil): A type of granulated Eosinophil (e’-o-SIN-o-fil): A type - Ependymal (e-pen-DI-mal) cells: A type of neu Epicardium (ep’-i-KAR-de-um): The thin outer layer superficial The (ep’-i-DERM-is): Epidermis the organ in Epididymis (ep’-i-DID-i-mis): An Epiglottis (ep’-i-GLOT-is): A part of the larynx layer outer The (ep’-i-MI-ze-um): Epimysium outer- Epineurium (ep’-i-NYOO-re-um): The Epiphyseal (ep’-i-FIZ-e-al) line: A line of calci- Epiphyseal plate: A region of cartilage between (en-DO-ste-um): A membrane lin- Endosteum (en-DO-ste-um): A layer of Endothelium (en’-do-THE-le-um): Enzyme (en’-do-PLAZ-mik re- (en’-do-PLAZ-mik reticulum Endoplasmic Glossary 180 Glossary

External respiration: The exchange of respiratory allow little or no movement between bones. gases between the lungs and the bloodstream. Fibrous tunic: The outer wall of the eyeball that Extracellular environment (ek’-stra-CEL-yoo-lar is composed of dense connective tissue, it en-VI-ron-ment): The body space outside the contains the sclera and the cornea. plasma membrane of cells. Filum terminale (FI-lum ter-mi-NAL-e): Connective (ECF): The fluid outside the tissue that extends beyond the conus medul- plasma membrane of cells, including intersti- laris of the spinal cord inferiorly into the tial fluid and blood plasma. coccyx. Fimbriae (FIM-bre-e): The fingerlike extensions F of the uterine tube at its proximal end (near the ovary). Facet (FA-set): A smooth articular surface on a Fissure (-er): A cleft or groove separating bone. two parts, such as the cerebral hemispheres of Falciform ligament (FAL-si-form LIG-a-ment): the brain; a deep sulcus of the brain. A part of the parietal peritoneum that is Flagellum (fla-JEL-um): A single, long extension located between the right and left lobes of of a cell composed of protein filaments to the liver. provide mobility. In human cells, it is found (see Uterine tube). only in sperm cells. Fascia (FASH-e-a): A sheet or band of dense Flexion (FLEK-shun): Movement of a body connective tissue that structurally supports part such that the angle between bones is organs and tissues. Deep fascia surrounds decreased. muscle, and superficial fascia separates the Foramen (fo-RA-men): An opening or passage skin and muscle layers. through bone. Plural form is foramina. Fascicle (FAS-i-kul): A bundle of Foramen magnum (MAG-num): The large fibers (cells) that forms a part of a muscle. opening at the base of the skull through which Fat: A lipid compound formed from one mol- passes the spinal cord. ecule of glycerol and three molecules of fatty Fossa (FOS-a): A shallow depression or groove acids. It is the body’s most concentrated in a bone. form of energy, and also serves to insulate Fourth ventricle (forth VEN-tri-kul): The cavity from external temperature changes. It is in the brain located between the cerebellum stored within cells comprising . and the midbrain and pons. Fauces (FAW-ses): The opening into the pharynx Fovea centralis (FO-ve-a cen-TRAL-is): The from the oral cavity (mouth). region of the retina that consists of cone Feces (FE-sez): Waste material discharged from cells, but no rod cells; it is the area of high- the large intestine during defecation. est visual acuity (sharpness of vision). Fertilization (fer’-ti-li-ZA-shun): The union of a Frontal plane: A plane that extends in a verticle sperm cell with a secondary oocyte. direction dividing the into front Fetus (FE-tus): The early developmental stage (anterior) and back (posterior) portions. Also from eight weeks after fertilization to the called the . time of birth. (FI-bro-blast): A large cell in connec- G tive tissue that manufactures much of the intercellular material. Gallbladder (GAWL-blad-er): A small saclike Fibrous (FI-brus) joint: One of three general organ located beneath the liver that stores bile. types of joints in the body. Fibrous joints are Gamete (ga-MET): A sex cell. It may be male characterized by the presence of dense con- (sperm cell) or female (oocyte). nective tissue between opposing bones. They GLOSSARY 181

(he’-mo-GLO-bin): A complex (he’-mo-GLO-bin): A complex system (see Osteon). protein in red blood cells involved in the in involved cells blood red in protein transport of oxygen and carbon dioxide. etes and sex hormones. In the male it is the the male it is the sex hormones. In etes and is the ovaries. in the female it testes, and cell bodies, that contains neuron nal cord axons, and dendrites, and nonmyelinated gray or non-white in color. therefore appears serosa of the stomach (or large fold of the that covers over the visceral peritoneum) abdominal cavity. and the trunk. between the thigh is gyri. cerebral surface of the brain. Plural composed of columns of keratinized cells. composed of columns of keratinized the hair rounding the root of a hair where originates. by the roof of the mouth. It is formed is lined the maxillary and palatine bones and with mucous membrane. coli intestine that form when the taenia muscle contracts. neck. The rounded, proximal end of a long bone. The proximal attachment of a muscle to a bone. through blood propels that cavity thoracic the circulatory network. duction of blood cells in the red bone mar- row. Also called hemopoiesis. Hepatic (he-PAT-ic): Pertaining to the liver. (GO-nad): An organ that produces gam- produces that organ An (GO-nad): and spi- in the brain : Nerve tissue Gray matter A o-MEN-tum): (GRA-ter Greater omentum located body the of region (groyn): The Groin sense of taste. Gustation (gus-TA-shun): The convolution on the Gyrus (JI-rus): An upfolding : A threadlike outgrowth of the skin that is that skin the of outgrowth threadlike A Hair: - : A cluster of epithelial tissue sur Hard palate (PAL-at): The anterior portion of large Haustra (HAWS-tra): The pouches in the Haversian to the Head: The region of the body superior Heart: The hollow muscular organ within the Hematopoiesis (hem’-a-to-poy-E-sis): The pro- Hemoglobin H

substances. It may consist of a single consist of may It substances.

maxillary bones and mandible. Also called maxillary bones and mandible. Also the gums. secrete cell or a multicellular arrangement. distal end of the penis. in the specialized capillary networks located kidney cortex, each of which is encapsulated of the by a Bowman’s capsule. It is part kidney of site the is and nephron, kidney filtration. from the pharynx. serves as the preferred energy source by the body. posed of glucose subunits that is manufac- tured by the liver to serve as a storage form of energy. Also mucus. goblet, that secretes of a shape called a mucus cell. lular organelle characterized by a series of flattened, hollow cisternae. It serves as a site of anabolic activities. types of glands in the stomach mucosa that mucosa that glands in the stomach types of gastric juice. contributes to the synthesize to needed information the tains chain. one complete polypeptide organs. the ovaries. epithelial cells covering ment prior to birth. covering the alveolar processes of the cell bodies located outside the central nervous the central nervous located outside cell bodies system. : A specialization of epithelial tissue to Gland: A specialization of epithelial tissue Glans penis (glanz PE-nis): The slightly enlarged, Glomerulus (glo-MER-yoo-lus): One of many larynx Glottis (GLOT-is): The opening into the that Glucose (GLOO-kos): A monosaccharide Glycogen (GLI-ko-jen): A polysaccharide com- : A unicellular gland, often in the Golgi apparatus (GOL-je ap’-a-RAT-us): A cel- : Any one of several : Any one gland Gastric (GAS-trik) con- that molecule DNA a of segment A Gene: (jen’-i-TAL-ya): The reproductive Genitalia epithelium: A layer of Germinal (JER-mi-nal) period of develop- Gestation (jes-TA-shun): The Gingivae (jin-JI-ve): The mucous membrane (GANG-le-on): A cluster of neuron neuron of A cluster (GANG-le-on): Ganglion Glossary 182 Glossary

Hepatic portal circulation: A circulatory network Infundibulum (in’-fun-DIB-yoo-lum): The nar- within the systemic system that involves the row connection between the hypothalamus of transport of blood from the alimentary canal the brain and the pituitary gland. Also, the to the liver. Its main vessel is the hepatic funnel-shaped distal end of the uterine tube portal vein. that opens near an ovary. Hilum (HI-lum): An area of an organ, usually a Ingestion (in-GES-chun): The intake of food or depression, where blood vessels and nerves liquid by the mouth. enter or exit. Also called a hilus. Inguinal (IN-gwi-nal): Pertaining to the groin (HIS-to-lo-je): The microscopic study region (between the hip and thigh). of tissues. Insertion (in-SER-shun): The attachment of a Homeostasis (ho’-me-o-STA-sis): A condition muscle by its tendon to a movable bone. of equilibrium, or physiological stability, of Inspiration (in-spi-RA-shun): The act of drawing body systems, in which the internal environ- air into the lungs. Also called . ment of the body remains relatively constant. Integumentary (in-teg’-yoo-MEN-tar-e): Pertaining Homologous (ho-MOL-o-gus): Two organs that to the skin and its accessory organs. correspond in structure, position, and origin. Intercalated disk (in-ter’-ka-LA-ted disk): A Horizontal plane: A plane that extends perpen- transverse thickening of a cardiac muscle dicular to the length of the body, dividing cell’s sarcolemma at its boundary with an it into superior and inferior portions. Also adjacent cell. It aids in the conduction of an called . impulse from one cardiac cell to another. Hormone (HOR-mon): A substance secreted by Intercellular (in’-ter-SEL-yoo-lar) environment: endocrine tissue that changes the physiologi- The area between cells. cal activity of the target cell. Internal (in-TER-nal): A directional term describ- Hypodermis (hi’-po-DERM-is): The area of the ing a location deep to the surface of the skin body between the dermis of the skin and relative to something else. skeletal muscle. Internal nares (NAR-ez): The paired openings Hypothalamus (hi’-po-THAL-a-mus): The between the nasal cavity and the nasopharynx small, inferior portion of the diencephalon in through which air passes. Also called choanae. the brain. It functions mainly in the control Internal respiration: The exchange of respiratory of involuntary activities, including endocrine gases between the blood and body cells. gland regulation, , thirst, and hunger. Interstitial cells (in’-ter-STI-shul): Cells in the testes located between seminiferous tubules I that secrete testosterone. Also called cells of Leydig. Ileocecal valve (il’-e-o-SE-kal valv): A fold of Interstitial fluid (in’-ter-STI-shul FLOO-id): mucous membrane between the ileum (of the The portion of extracellular fluid that fills the small intestine) and the cecum (of the large tissue spaces between cells. Also called tissue intestine). Also called the ileocecal sphincter. fluid and intercellular fluid. Ileum (IL-e-um): The distal segment of the small Intervertebral disk (in’-ter-VER-te-bral disk): A intestine. that consists of a pad of Inferior (in-FER-e-or): A directional term located between two adjacent describing a location further from the head vertebrae. than something else. (in-TES-tin-al gland): A in the mucosa of the small intestine that secretes digestive enzymes. Also called crypt of Leiberkuhn. GLOSSARY 183 form is labia. inner ear. necting tubes of the tears. tion or release of glands. milk by the mammary villus of the small intestine located within a that transports fat. (an osteo- cartilage matrix that houses a cell lacunae. is form Plural chondrocyte). or cyte bone. ened bone matrix found in compact tube that mentary canal consisting of a large the pro- forms the feces, which is expelled by cess of defecation. to the rior part of the pharynx, which opens larynx esophagus (posteriorly) and to the (anteriorly). between organ in the located the pharynx and the trachea. from ing a structure that is located further relative to the vertical midline of the body another. between the posterior iris and the vitreous the to connected is It eyeball. the of humor vascular tunic by suspensory ligaments. of the peritoneum that extends between the liver and the medial margin of the stomach. Also called leucocyte. connective tissue that extends from one bone to another to provide a joint with structural stability. L for lip. Plural A synonym Labium (LA-be-um): of intercon- The system (LAB-i-rinth): Labyrinth produc- to the (LAK-ri-mal): Pertaining Lacrimal The production of Lactation (lak-TA-shun): vessel small lymphatic (lak-TE-al): A Lacteal chamber within bone or Lacuna (la-KOO-na): A hard- rings of (la-MEL-e): Concentric Lamellae - Large intestine: The final segment of the ali - Laryngopharynx (la-ring’-o-FAR-inks): The infe Larynx (LAR-inks): A box-like cartilaginous term describ- (LA-ter-al): A directional Lateral located structure transparent oval, An Lens: Lesser omentum (LES-er o-MEN-tum): A fold Leukocyte (LOO-ko-sit): A white blood cell. Ligament (LIG-a-ment): A band or cord of dense

present in the epidermis, nails, and hair. the small intestine. opposing bones. Also called articulation. in located A structure yoo-lar ap’-a-RAT-us): a kidney nephron that is composed of cells from the distal convoluted tubule and the response in secretes It afferent arteriole. to a decrease in blood pressure. bra-nus os’-i-fi-KA-shun): The development development The os’-i-fi-KA-shun): bra-nus connective tissue mem- of bone from fetal branes. into the body wall cavity a body inward of cavity. the sole of the foot faces inward such that medially. a culture bottle. eyeball It is located on the anterior side of the fibers that and is composed of smooth muscle the eye. regulate the amount of light entering eye sur- The iris is the colored part of the rounding the pupil. cells One of numerous clusters of endocrine within the pancreas. The space within a cell. The space K Keratin (KER-a-tin): A waterproofing protein (je-JOO-num): The middle segment of Jejunum (je-JOO-num): The middle segment two Joint (joynt): A point of contact between Juxtaglomerular apparatus (juks’-ta-glo-MER- J : The fluid within cells. : The fluid (ICF) fluid Intracellular (in’-tra-MEM- ossification Intramembranous A folding Invagination (in-vaj’-in-A-shun): of the foot Inversion (in-VER-zhun): Movement the body, such as in In vitro (in VE-tro): Outside vivo (in VE-vo): Inside the living body. In of the eye. Iris (I-ris): A part of the vascular tunic Islet of Langerhans (I-let of LANG-er-hanz): : environment (in’-tra-SEL-yoo-lar) Intracellular Glossary 184 Glossary

Lingual (LIN-gwal): Pertaining to the tongue; for Mammary (MAM-a-re) gland: A modified sweat example, the lingual frenulum that connects gland in the that serves as the gland of the tongue to the floor of the mouth. milk secretion for nourishment of the young. Lipid (LI-pid): An organic compound that is usu- Matrix (MA-triks): The intercellular material in ally insoluble in water, but soluble in alcohol, connective tissue. ether, and chloroform. It includes fats, phos- Mastication (mas’-ti-KA-shun): A synonym for pholipids, and steroids. the muscular act of chewing. Liver: A large digestive organ in the superior Medial (ME-de-al): A directional term describing right corner of the abdominopelvic cavity a part lying nearer to the vertical midline of that functions mainly in the interconversion the body relative to another part. of energy-storage molecules, detoxification of Mediastinum (me’-de-as-TI-num): A partition blood, and production of bile. between the two peural cavities in the chest Lumbar (LUM-bar): The region of the back that consists of the heart, part of the esopha- between the ribs and pelvis. Also called loins. gus, part of the trachea, and the major vessels (LOO-men): The potential space within of the heart. a tubular structure. Medulla (me-DUL-a): An inner, or deeper, part Lung: One of two large organs in the thoracic of an organ. For example, the medulla of the cavity that functions in the exchange of respi- kidneys and the medulla of the adrenal gland. ratory gases. Medulla oblongata (me-DUL-a ob’-long-GA-ta): Lymph (limf): The slow-moving fluid within The inferior part of the brain stem. lymphatic vessels of the lymphatic system. Medullary cavity (med-YOO-lar-e KAV-i-te): : A small, oval organ located within The potential space within the shaft of a long the network. bone that contains yellow marrow. Lymphatic tissue: A specialized type of connec- Membrane (MEM-bran): A thin sheet of tissue tive tissue that contains an abundance of that lines or covers body structures. It may . Also called lymphoid tissue. contain a thin layer of epithelial tissue and Lymphatic vessel: A hollow tubular structure connective tissue, or only connective tissue. similar to a vein that transports lymph in a Membranous labyrinth (MEM-bra-nus LAB-i- direction leading toward the heart. rinth): The portion of the inner ear located (LIM-fo-cit): A type of white blood inside the bony labyrinth that contains peri- cell lacking large granules in the cytoplasm lymph fluid. It consists of the membranous that plays a central role in immunity. semicircular canals, the saccule and utricle, Lysosome (LI-so-som): A cellular organelle that and the cochlear duct. contains digestive enzymes. Meninges (me-NIN-jez): The three membranes covering the brain and spinal cord. M Mesentery (MES-en-ter’-e): A fold of the perito- neum that attaches the small intestine to the (MAK-ro-faj): A large phagocytic posterior abdominal wall. cell that originated from a monocyte. Metabolism (me-TAB-o-lizm): The sum of all Macula (MAK-yoo-la): One of the sensory struc- chemical reactions occurring in the body, tures in the vestibule of the inner ear. It including anabolic (synthetic) and catabolic serves as a for static equilibrium. (decomposition) reactions. Macula lutea (MAK-yoo-la LOO-te-a): A yellow- Metacarpus (met’-a-KAR-pus): A collective term colored depression in the retina of the eye. for the five bones (each of which is called a Malleus (MAL-e-us): The lateral ear bone that metacarpal) of the palm of the hand. contacts the tympanic membrane; the ham- Metatarsus (MET-a-tar-sus): A collective term mer. for the five bones (each of which is called a metatarsal) of the foot. GLOSSARY - 185 tissue in the body, characterized by its specializa body, characterized tissue in the tion to contract. an of wall the within tissue muscle smooth organ. cover over the axons of mented insulative that is produced by many peripheral neurons neuron axon that is covered Schwann cells. A is said to be myelinated. by the myelin sheath is composed of wall, which heart of the layer cardiac muscle tissue. the ponent of a muscle fiber, which extends of thin length of the fiber and is composed and thick filaments of protein. muscle layer in the wall of the uterus. is derived from the epidermis and develops is derived from the epidermis and atthe distal end of the fingers and toes. by lined with mucous membrane and divided chambers. left and right into septum nasal the that nasal cavity into right and left chambers and cartilage covered is composed of bone with mucous membrane. pharynx, which transports air of the portion between the internal nares and the orophar- ynx. tubular structures within each kidney where the functions of filtration, reabsorption, and secretion occur. of a bundle of neuron axons invested and surrounded by connective tissue and blood vessels, which functions in the conduction of an impulse from one area of the body to another. : One of the four primary types of types four primary of the : One tissue Muscle of layer A (mus’-kyoo-LAR-is): Muscularis A white, seg- Myelin sheath (MI-e-lin sheth): The primary Myocardium (mi’-o-KAR-de-um): A rod-shaped com- Myofibril (mi’-o-FI-bril): Myometrium (mi’-o-ME-tre-um): The smooth N that Nail: A thin, hard plate of mostly keratin is Nasal cavity: The space within the nose that Nasal septum: A vertical partition dividing the Nasopharynx (na’-so-FAR-inks): The superior Nephron (NE-fron): One of many microscopic, Nerve: An organ of the nervous system composed -

discharging urine from the urinary bladder to discharging urine called . the exterior. Also between the diencephalon brain stem, located serves as a relay center for and the pons. It the mesencephalon. impulses. Also called of the outer ear and membrane tympanic of the inner ear. It is an the bony labyrinth that houses the three ear epithelial-lined space ossicles. Also called the tympanic cavity. it into vertically through the body, dividing unequal right and left portions. - filled with cyto the cell membrane sions of the absorptive serve to increase plasm that of the cell. surface area lular organelle that consists of a double layer lular organelle that consists of a double the cata- of plasma membrane where many of bolic activities of the cell take place. each of nucleus into two daughter nuclei, which contain the same genetic composition is fol- as the original parent. When of the lowed by cytokinesis, equal division whole cell results. called the left atrioventricular valve. Also bicuspid valve. hair-covered body surface area over the sym- physis pubis in females. that lines a body cavity or organ and contains mucous called Also mucus. secrete that cells membrane. from mucous cells. tissue and its associated connective tissue that of move- the production in mainly functions ment of the skeleton. (mik’-too-RISH-un): The act of act of The (mik’-too-RISH-un): Micturition the of part superior The (MID-bran): Midbrain ear between the Middle ear: The area of the extends plane that A Midsagittal (MID-sag-i-tal): cel A (mit’-o’-KON-dre-on): - exten Microscopic (mi’-kro-VIL-i): Microvilli Glossary (mi-TO-sis): The division of a cell’s Mitosis (mi-TO-sis): The division of a Mitral valve (MI-tral valv): A synonym for the Mons pubis (monz PYOO-bis): The elevated, Mucosa (myoo-KO-sa): An epithelial membrane thick fluid secretion A (MYOO-kus): Mucus Muscle: An organ composed of skeletal muscle fiber: A synonym for . Muscle 186 Glossary

Nerve impulse: A wave of negative charges (depolarization) that propagates along the Optic (OP-tik): Pertaining to the sense of vision outer surface of the plasma membrane of a or to the eye. conductive cell, such as a neuron. Also called Optic chiasma (OP-tik ki-AZ-ma): The point at an action potential. which the two optic nerves cross on the ven- Neurilemma (noo’-ri-LEM-a): The outer layer of tral aspect of the brain. a myelin sheath associated with a nerve fiber Optic disk: The area on the retina where the that contains the nucleus and much of the optic nerve exits the eye and contains no rod cytoplasm of a Schwann cell. or cone cells. Also called the blind spot. Neuroglia (noo’-ROG-le-a): Supportive cells of Orbit (OR-bit): One of two large depressions in the nervous system that are most prevalent in the skull that is bordered by seven bones and the brain and spinal cord. houses the eyeball and associated structures. Neuromuscular junction (noo’-ro-MUS-kyoo- Also called the eye socket. lar JUNK-shun): The area of contact between Organ (OR-gan): An organized combination of the terminal end of a motor neuron and the two or more different types of tissues that sarcolemma of a skeletal muscle fiber. performs a general function. Neuron (NOO-ron): A cell of nerve tissue char- Organ of Corti (KOR-ti): The structure within acterized by its specialization to conduct the inner ear that contains receptor cells sen- impulses (conductivity). sitive to sound vibrations. Neurotransmitter (noo’-ro-TRANS-mit-er): A Organelle (or-gan-EL): A component of a cell molecule that transmits or inhibits the trans- that has a consistent, similar structure in mission of a nerve impulse from one neuron other cells and performs a particular function. to another across a synapse. Organic (or-GAN-ik): A chemical substance (NOO-tro-fil): A type of granular, whose structure is based on a carbon skeleton. phagocytic white blood cell characterized by Organism (OR-gan-izm): A complete living a cytoplasm that stains pink in a neutral stain. being; a whole individual. Node of Ranvier (ran’-ve-A): A gap in the myelin Orifice (OR-i-fis): An opening into the body or sheath covering a nerve fiber, which acceler- into a structure. ates the rate of impulse conduction. Origin (OR-i-jin): The point of attachment of a Nucleolus (noo-KLE-o-lus): A spherical body muscle’s tendon to a stationary bone. within the nucleus of a cell that is not bound Oropharynx (or’-o-FAR-inks): The middle por- by a plasma membrane, which functions in tion of the pharynx, located between the the storage of ribosomal RNA. nasopharynx and the laryngopharynx. The Nucleus (NOO-kle-us): The largest structure oral cavity opens into it (by way of the fau- in a cell, it contains the genetic material to ces). determine protein structure and function, the Osseous (OS-e-us): Pertaining to bone. DNA, and is enveloped by a double-layered Ossification (os’-i-fi-KA-shun): Bone formation. plasma membrane. Also called osteogenesis. Osteoblast (OS-te-o-blast’): A type of bone cell O characterized by its mobility and by its ability to produce bone matrix. Occipital (ok-SIP-i-tal): Pertaining to the lower Osteoclast (OS-te-o-klast’): A type of bone cell back portion of the head. characterized by its ability to dissolve bone Olfactory (ol-FAK-tor-e): Pertaining to the sense matrix. of smell. Osteocyte (OS-te-o-sit’): A type of bone cell Oocyte (O-o-sit): A gamete produced within an characterized by its immobile location within ovary. Also called ovum or egg. a lacunus and by a reduced ability to produce bone matrix. GLOSSARY - 187 ear.

the epimysium of muscle that invaginates inward to divide a muscle into bundles. ric acid into , can digest protein. heart (the space between the outer wall of the pericar- visceral pericardium) and the parietal dium that contains pericardial fluid. membrane associated with the heart that is composed of two layers, an inner visceral pericardium and an outer parietal pericar- dium. of dense connective tissue that envelopes cartilage. membranous labyrinth of the inner outer covering the heart. the heart. membrane covering outer serous sac. the pericardial Also called to attached covering membrane serous outer cavity. the walls of the abdominopelvic with each lung. It is membrane associated thoracic wall. attached to the inner is located between the glands, each of which on muscle masseter and the cheek of the skin a side of the face. thorax, or chest. trunk region, or pelvis. nopelvic cavity bordered by the pelvis. and the by the two pelvic (innominate) bones sacrum. the ure- of the male through which most of thra extends. stomach by zymogenic (chief) cells in the mucosa in the inactive form of pepsinogen that, when activated by the presence of hydrochlo Perimysium (par’-i-MI-se-um): An extension of (par’-i-KAR-de-al) cavity: A narrow A cavity: (par’-i-KAR-de-al) Pericardial Pericardium (par’-i-KAR-de-um): The serous Perichondrium (par’-i-KON-dre-um): A layer The fluid within the Perilymph (PAR-i-limf): (par’-i-KAR-de-um): The The (par’-i-KAR-de-um): pericardium Parietal The peritoneum (par’-i-to-NE-um): Parietal outer serous pleura (PLOO-ra): The Parietal glands: A pair of salivary Parotid (pa-ROT-id) to the ventral Pectoral (PEK-tor-al): Pertaining of the Pelvic (PEL-vik): Pertaining to the base - Pelvic cavity: The inferior portion of the abdomi formed Pelvis: The bowl-like base axial skeleton organ reproductive The external (PE-nis): Penis Pepsin (PEP-sin): An enzyme initially secreted viding di

receptor located in the dermis that responds receptor located in the dermis that to touch (pressure). mouth. structure forming the roof of the and the The anterior end is the hard palate, posterior end is the soft palate. in the located posterior to the stomach secretes abdominal cavity. The pancreas that regu- digestive enzymes and hormones late blood sugar. tion. extends vertically through the body between the stapes and the inner ear. between the stapes that produces gametes reproductive organ and female sex hormones. from a Graafian follicle in secondary oocyte an ovary. it into unequal right and left portions. tik di-VI-zhun): The component of the system that stimulates nervous autonomic activities that conserve body energy. four or five pea-shaped glands embedded into the posterior side of the thyroid gland. of a cavity or organ. secretes hydrochloric acid and bone tissue in adult compact bone such that bone such that in adult compact bone tissue a surrounds matrix concentrically bone the blood vessel. Also containing a central canal system. called a Haversian Pacinian corpuscle (pa-SIN-e-an KOR-pus-el): A Palate (PAL-at): The mucous membrane-lined Pancreas (PAN-kre-as): A soft, oblong organ projec- Papilla (pa-PIL-a): A small finger-shaped Parasagittal (par’-a-SAJ-i-tal): A plane that P (O-tik): Pertaining to the ear. Otic (O-tik): Pertaining opening Oval window: The membrane-covered gonad, or primary Ovary (O-var-e): The female The release of a Ovulation (ov-yoo-LA-shun): (par’-a-simp-a-THE- division Parasympathetic Parathyroid (par’-a-THI-royd) gland: One of Parietal (pa-RI-e-tal): Pertaining to the outer wall : A cell in the stomach mucosa that (OS-te-on): An organized arrangement of arrangement organized An (OS-te-on): Osteon Glossary 188 Glossary

Perineum (par’-i-NE-um): The area between the Plasma (PLAZ-ma): The extracellular fluid that anus and the posterior border of the external forms a portion of blood. genitalia. Plasma cell: A differentiated white blood cell that Perineurium (par’-i-NYOO-re-um): An exten- secretes antibodies. sion of the epineurium of a nerve that invagi- Plasma membrane: A microscopic barrier associ- nates inward to wrap around bundles of nerve ated with cells composed mainly of a phos- fibers. pholipid bilayer and protein. The outer Periosteum (par’-e-OS-te-um): The connective plasma membrane of a cell is also called the tissue covering around a bone that is impor- cell membrane. tant in bone growth, nutrition, and repair. Platelet (PLA-te-let): A formed element of blood Peripheral (per-I-fer-al) nervous system (PNS): that is active in blood clot formation. The division of the nervous system consist- Pleura (PLOOR-a): The serous membrane asso- ing of nerves and ganglia located between the ciated with the lungs. It consists of an central nervous system and the body surfaces. inner visceral pleural and an outer parietal Peritoneum (par’-i-to-NE-um): The extensive pleura. Plural form is pleurae. serous membrane associated with the abdom- Pleural cavity: A narrow space between the inopelvic cavity. visceral and parietal pleurae that contains Peritoneal (par’-i-to-NE-al) cavity: The space pleural fluid. between the parietal peritoneum and the Plexus (PLEKS-us): A network of interconnect- visceral peritoneum that contains a small ing nerves, veins, or lymphatic vessels. amount of fluid. Pons (ponz): A part of the brain located between Peyer’s patches: Clusters of lymphatic tissue the midbrain and the medulla oblongata. containing numerous white blood cells that Popliteal (pop’-li-TE-al): Pertaining to the area are located in the wall of the small intestine. posterior to the knee joint. Phalanx (FA-lanks): A bone of a digit (finger or Posterior (po-STER-e-or): A directional term toe). Plural form is phalanges. describing the location of a part being toward Pharynx (FAR-inks): A tube that extends from the back or rear side relative to another part. the level of the internal nares to its union In humans it is also known as dorsal. with the larynx, which transports air, food, Posterior horn: A region of the spinal cord gray and liquid. matter containing cell bodies. Pia mater (PE-a MA-ter): The innermost of the Also called the ventral horn. three meninges surrounding the brain and Posterior root: The structure merging with the spinal cord. spinal cord on its posterior aspect that con- Pineal (pi-NE-al) gland: A small endocrine gland tains sensory nerves. Also called the dorsal located at the posterior end of the diencephalon, root. forming a part of the roof of the third ven- Prepuce (PRE-poos): The skin that partially tricle. covers the glans of the penis (in the male) or Pituitary (pi-TOO-i-tar-e) gland: A small, func- clitoris (in the female). tionally important endocrine gland located Process (PRO-ses): A prominent projection on inferior to the hypothalamus and attached a bone. to it by way of a short stalk. Also called the Pronation (pro-NA-shun): Movement of the hypophysis. hand such that the palm is turned downward (pla-SEN-ta): A structure whose origin (inferiorly) or backward (posteriorly). is shared by embryonic cells and the uter- Prostate (PRO-stat) gland: A walnut-shaped ine lining that provides a means of material gland surrounding the urethra as it emerges transport between the mother and developing from the urinary bladder in males. Its secre- unborn child. tions contribute to semen. GLOSSARY 189 bricate lu

- molecules dur be crossed by gas that must alveolar the of consists exchange. It gas ing the and membrane, basement a epithelium, of a capillary. endothelium rod and cone cells. of the eye that contains to the parietal peri- a structure lying external toneum. com- cell a of cytoplasm the within structure protein that serves as an posed of RNA and messenger RNA during attachment site for protein synthesis. eye that detects very low levels of light. the humerus to the scapula. axis. bone around its own (longitudinal) the inner ing between the middle ear and auditory ear that is not in contact with the ossicles. as the of an organ with a large lumen, such stomach or vagina. vestibule of the inner ear that houses the vestibule of the inner ear that houses receptors of static equilibrium. the body into right and left portions, and includes the midsagittal plane (dividing into equal halves) and the parasagittal plane (dividing into unequal portions). glands deposited into the mouth to and begin digestion of food before swallow- ing. crine glands in the facial region that secrete saliva into the mouth to initiate the digestive process. : The barrier in the lungs in the lungs barrier : The membrane Respiratory light-sensitive inner layer Retina (RET-i-na): The PertainingRetroperitoneal (re’-tro-par’-i-to-NE-al): to spherical Ribosome (RI-bo-som): A microscopic, the of retina the in cell A : Rod cuff: A group of four muscles that attach Rotator of a Rotation (ro-TA-shun): The movement - Round window: The membrane-covered open mucosa Rugae (ROO-je): Folds or ridges in the S the Saccule (SAK-yool): One of two sacs within Sagittal (SAJ-i-tal): A vertical plane that divides Saliva (sa-LI-va): A fluid secretion by the salivary Salivary (SAL-i-var-e) gland: One of several exo-

of responding to a stimulus by initiating a of responding to a stimulus by initiating nerve impulse. large intestine. the Bowman’s consisting of nephron kidney capsule and glomerulus. within the of each kidney. kidney to ten cone-shaped structures in each extending from the medulla to the cortex, which contain the renal tubules. the to hilum the from extending kidney each medulla, which contains the renal pelvis. of the kidney consisting of a microscopic tube extending from Bowman’s capsule to a col- lecting duct. The functions of reabsorption and secretion occur across its walls. union of the stomach and small intestine that union of the stomach between controls the movement of material them. Also called the pyloric valve. indicating a body part that is located nearer is located nearer a body part that indicating attachment to the or point of to the origin opposite of distal. trunk than another; and the lungs, through lung capillaries, to of the heart. back to the left atrium in the eye through which center of the iris light passes. muscle at the circular band of smooth posed of subunits. posed of R Receptor (re-SEP-tor): A structure that is capable of the Rectum (REK-tum): The distal portion Renal (RE-nal): Pertaining to the kidneys. a of portion The (KOR-pus-el): corpuscle Renal Renal pelvis (PEL-vis): A membrane-lined basin eight about of One Renal pyramid (PIR-a-mid): Renal sinus (SI-nus): A potential space within Renal tubule (TOO-byool): A part of a nephron (PROKS-i-mal): A directional term A directional (PROKS-i-mal): Proximal flow : The circuit of blood Pulmonary circulation small hole through the Pupil (PYOO-pil): The A (pi-LOR-ik SFINC-ter): Pyloric sphincter - com compound organic An (PRO-ten): Protein Glossary 190 Glossary

Sarcolemma (sar’-ko-LEM-a): The plasma mem- Seminiferous tubule (sem’-i-NIF-er-us TOO- brane covering the outer surface of a muscle byool): A microscopic, tightly packed tube fiber. within each testis where sperm cells develop. Sarcomere (SAR-ko-mer): A contractile micro- Septum (SEP-tum): A barrier between two scopic subunit of striated muscle (skeletal and spaces, such as the interventricular septum of cardiac muscle tissue). the heart and the nasal septum. Sarcoplasm (SAR-ko-plazm): The cytoplasm of a Serosa (ser-O-sa): Any serous membrane. Also, muscle fiber. the outer serous membrane layer of a visceral Schwann cell: A type of neuroglial cell that forms organ. myelin sheaths around axons of peripheral Serous membrane (SER-us MEM-bran): An epi- nerves. thelial membrane that lines a body cavity or Sclera (SKLE-ra): The posterior part of the outer, covers an organ, and secretes small amounts fibrous tunic covering the eyeball; the white of fluid. of the eye. Sesamoid (SES-a-moyd) bones: Small bones Scrotum (SKRO-tum): An external genital organ formed and located within major or of the male consisting of a skin-covered sack ligaments. For example, the (kneecap) that contains the testes. is a sesamoid bone. Sebaceous (se-BA-shus) gland: An Sigmoid colon (SIG-moyd KO-lon): The distal located in the dermis that secretes an oily sub- segment of the colon located between the stance called sebum. It is usually associated descending colon and the rectum. with a hair follicle. Sinoatrial node (sin’-o-A-tre-al nod) (SA node): Sebum (SE-bum): An oily secretion of a seba- A cluster of specialized cardiac muscle cells in ceous gland. the wall of the right atrium that initiate each Secretion (se-KRE-shun): A substance produced cardiac cycle. and released by a cell that serves a useful Sinus (SI-nus): A space within a bone lined with benefit. mucous membrane, such as the frontal and Semen (SE-men): A reproductive fluid discharged maxillary sinuses in the head. Also, a modi- by a male during ejaculation that contains fied vein with an enlarged lumen for blood sperm cells and secretions from the seminal storage. vesicles, prostate gland, and bulbourethral Skeletal muscle tissue: One of three types of glands. muscle tissue in the body characterized by the Semicircular canal (se’-mi-SER-kyoo-lar ca- presence of visible striations and conscious NAL): One of three looping canals in each control over its contraction. It attaches to temporal bone that form a part of the inner bones to form the muscles of the body. ear. It contains perilymph fluid and the Skull: The group of bones that make up the sup- receptors for equilibrium. porting framework and body of the head. Semilunar (SL) valve (sem-i-LOO-nar valv): Small intestine: The organ of the alimentary One of two heart valves located between a canal located between the stomach and the ventricle and a major artery. The aortic valve large intestine that functions in the final is located between the left ventricle and aorta, digestion and absorption of nutrients. and the pulmonary valve is located between Smooth muscle: One of three types of muscle the right ventricle and pulmonary trunk. tissue in the body characterized by the lack Seminal vesicle (SEM-i-nal VES-i-kel): One of a of visible striations and unconscious control pair of convoluted glands of the male repro- over its contraction. It forms part of the walls ductive system located posterior to the uri- of hollow organs and blood vessels. nary bladder that secretes part of the semen. GLOSSARY 191 rvous

ne

(sub-LING-wal) glands: A pair of sali- (sub-LING-wal) system that functions mainly in stimulating emergency responses (fight or flight). axon of one neuron and the dendrite or cell body of another neuron. action that assists the prime mover by keep- ing other structures stable. tissue and adipose tissue deep to the dermis of to the dermis of adipose tissue deep tissue and - and super Also called hypodermis, the skin. ficial fascia. the floor of the mouthvary glands located in deep to the mucous membrane. glands located along the A pair of salivary the of floor the in jaw the of surface inner submaxillary glands. mouth. Also called external to a mucous nective tissue located membrane. secretes crine gland located in the skin that sweat. Also called . sion. that is part of a indicating the location term relative toward or nearer to the body surface to another. nearer to cating the location of a part that is called Also another. than region head the craniad or cephalad. hand is the forearm such that the palm of the turned anteriorly or superiorly. joint that permits little or no movement between opposing bones. skin that secretes sweat. Also called sudorifer- ous gland. zhun): A division of the autonomic LA-yer): The layer of loose connective The layer of loose LA-yer): (sin-APS): The junction between the between junction (sin-APS): The Synapse Synergist (SIN-er-jist): A muscle in a group Sublingual glands: Submandibular (sub’-man-DIB-yoo-lar) - con A layer of (sub’-myoo-KO-sa): : An exo- Sudoriferous (soo’-dor-I-fer-us) gland depres- Sulcus (SUL-kus): A shallow groove or Superficial (soo’-per-FISH-al): A directional indi- Superior (soo-PER-e-or): A directional term of Supination (soo’-pi-NA-shun): The rotation fibrous Suture (SOO-cher): A type of tight-fitting Sweat gland: An exocrine gland located in the di-VI- Sympathetic division (simp’-a-THE-tik (sub’-kyoo-TA-ne-us (sub’-kyoo-TA-ne-us layer Subcutaneous (SFENK-ter): A circular band of of (SFENK-ter): A circular band

For example, a somatic cell is any body cell For example, a somatic other than a sex cell. system that conveys the peripheral nervous with conscious sensory impulses associated and motor activities. reproductive the male in bundle of tissue from the epididymis to system extending the ductus consisting of the inguinal canal, vessels, deferens, cremaster muscle, blood tissue. lymphatics, nerves, and connective called gametes, or reproductive cells. Also sperm cells. Singular form is spermatozoon. opening, smooth muscle surrounding an of which serves to control the movement materials through. the through extends that system nervous peripheral vertebral canal and connects the nervous system with the brain. another extend between the spinal cord and part of the body. in the the lymphatic system and is located upper left region of the abdomen behind the stomach. characterized by the presence of spaces filled spicules between thin bone red marrow with called trabeculae. the alimentary canal located between the esophagus and small intestine that plays a prominent role in digestion. narrow space between the arachnoid and pia mater surrounding the brain and spinal cord, which contains circulating cerebrospi- nal fluid. forming the roof of the mouth, consisting of consisting of the roof of the mouth, forming - mucous mem covered with skeletal muscle brane. (so-MA-tik): Pertaining to the body. to the body. Pertaining Somatic (so-MA-tik): of system: The component Somatic nervous A narrow Spermatic cord (sper-MA-tik kord): Spermatozoa (sper-ma’-to-ZO-a): The male Sphincter Spinal cord: A long, narrow organ of the central nerve: One of 31 pairs of nerves that Spinal part of Spleen: An soft, glandular organ that is Spongy bone: One of two types of bone tissue, Stomach (STO-muk): A large, hollow organ in Subarachnoid space (sub-a-RAK-noyd spas): The : The posterior portion of the bridge of the portion posterior palate : The Soft Glossary 192 Glossary

Synovial joint (sin-O-ve-al joynt): A type of Thorax (THOR-aks): The region of the trunk joint characterized by the presence of a mem- located superior to the diaphragm. Also brane-lined cavity, called the synovial cavity, called the chest. between opposing bones. Thrombocyte (THROM-bo-sit): The formed : The liquid secretion of epithe- elements in blood that play a prominent role lial cells in the lining a in blood clotting. Also called platelets. synovial joint, which serves as a lubricant and Thymus (THI-mus) gland: A glandular lym- shock absorber. phatic organ located superior to the heart that System (SIS-tem): An organized combination of produces T lymphocytes during early child- organs and associated structures that share a hood, and degenerates by adulthood. common function. Thyroid cartilage (THI-royd CAR-ti-lij): The Systemic circulation: The major circulatory net- largest piece of hyaline cartilage of the larynx. work of the body that carries oxygenated Also called Adam’s apple. blood from the left ventricle throughout the Thyroid gland: An endocrine gland located on body (except the lungs), and returns deoxy- the anterior side of the neck that secretes hor- genated blood to the right atrium. mones involved in growth and metabolism, and maintains calcium levels in the blood. T Tissue (TI-shoo): A group of similar cells that combine to form a common function. (TAR-sus): The seven bones of the ankle Tongue (tung): The muscular organ of the diges- as a collective unit. tive system that is anchored to the floor of Tectorial membrane (tek-TOR-e-al MEM- the mouth and wall of the pharynx, and bran): A thin membrane in the inner ear that which plays a role in swallowing and speech projects over the receptor hair cells of the formation. organ of Corti. Tonsil (TON-sil): A small organ of the lymphatic Tendon (TEN-don): A band of dense connective system that consists of an aggregation of fixed tissue that extends from the muscle to attach lymphocytes and connective tissue embed- to a bone. ded in a mucous membrane. There are three Testis (TES-tis): One of a pair of male gonads pairs (pharyngeal, palatine, and lingual), all (sex glands) located within the scrotum that of which play a role in the immune response. produces sperm cells and testosterone. Plural Trabecula (tra-BEK-yoo-la): A thin plate of bone form is testes. within spongy bone tissue. Also, a band of Thalamus (THAL-a-mus): A bilobed endocrine supportive connective tissue extending to the gland located in the anterior neck region that interior of an organ from its outer wall. produces hormones influencing growth and Trachea (TRA-ke-a): An organ of the respiratory metabolism, and maintains calcium levels in system that consists of a long tube supported the blood. by rings of cartilage extending from the phar- Thoracic cavity (tho-RAS-ik CAV-i-te): The part ynx to the bronchi. of the anterior (ventral) body cavity located Transverse colon (TRANS-vers KO-lon): The superior to the diaphragm. segment of the colon that extends from its Thoracic duct: The main collecting trunk of the union with the ascending colon to its union lymphatic circulation, which extends along with the descending colon. the back of the chest to the right subclavian Tricuspid valve (tri-KUS-pid valv): The heart vein. It drains lymph from all areas of the valve located between the right atrium and body but the right side of the head, neck, right ventricle. Also called the right atrioven- chest, and right arm. tricular (AV) valve. GLOSSARY 193 the female reproductive system extending system extending reproductive the female uterus. the vulva and the between taining blood vessels. to the heart. from body tissues part nearer to the anterior, the location of a body relative to another. or front side, of the Also called anterior. the tho- anterior side of the trunk containing racic and abdominopelvic cavities. that connects with the spinal cord. heart that highly muscular chambers of the during their push blood into major arteries contraction. network deoxygenated blood from a capillary and conveys it to a larger vein. extending tube closed-end small, A diks): from the cecum of the large intestine. cerebellartwo the separates that cerebellum the of hemispheres. that extending through the vertebral column is formed by the vertebral foramina of each vertebra, through which extends the spinal cord. is composed of 26 vertebrae and associated tissues. Also called the backbone, spine, or spinal column. fluid. In the cell, it is a membranous sac within the cytoplasm that contains cellular products or waste materials. opens into a larger cavity or canal. A vesti- bule is found in the inner ear, mouth, nose, and vagina. V organ of A tubular, muscular Vagina (va-JI-na): - con or (VAS-kyoo-lar): Pertaining to Vascular that transports blood Vein (van): A blood vessel term describing Ventral (VEN-tral): A directional located on the Ventral cavity: The body cavity nerve spinal a of branch motor The Ventral root: inferior, two the of One (VEN-tri-kul): Ventricle collects that vein small A (VEN-yool): Venule Vermiform appendix (VER-mi-form a-PEN- constricted part central The (VER-mis): Vermis cavity ka-NAL): A (VER-te-bral Vertebral canal Vertebral column: The skeleton of the back that Vesicle (VES-i-kul): A small sac containing a Vestibule (VES-ti-byool): A small space that

extends from a kidney to the urinary bladder extends from a kidney to the urinary and transports urine. that car- the urinary bladder to the exterior semen in ries urine in females and urine and males. floor of hollow muscular organ located at the urine. the pelvic cavity that temporarily stores and kidneys that is expelled out the urethra materials, contains water, metabolic waste and excess salts. ovaries to tubes that transport ova from the the uterus in the female reproductive system. Also called fallopian tubes or oviducts. in the female reproductive system that serves as a site of embryo implantation and develop- ment, and menstruation. skeletal muscle covered with mucous mem- brane at the posterior end of the soft palate. like structure containing the umbilical arter- like structure containing the umbilical a fetus ies and umbilical vein that connects with the placenta. cess on the surface of a bone. cess on the between the external audi- A thin membrane tympanic cavity, separat- tory canal and the from the middle ear. Also ing the external ear called the eardrum. appendages are attached, and includes the and includes attached, are appendages and back. chest, abdomen, (YOO-re-ter): A long, narrow tube that Ureter (YOO-re-ter): A long, narrow tube from Urethra (yoo-RE-thra): A tube extending Urinary bladder (yoo’-ri-NAR-e BLAD-der): A by the Urine (YOO-rin): The fluid produced Uterine tube (YOO-ter-in toob): One of two Uterus (YOO-ter-us): A hollow muscular organ Uvula (YOO-vyoo-la): A fingerlike projection of U The rope- (um-BIL-i-kal kord): (TOO-ber-kul): A small, rounded pro - rounded small, A (TOO-ber-kul): Tubercle membrane (tim-PAN-ik MEM-bran): Tympanic : The region of the body to which the which body to of the region : The Trunk Glossary 194 Glossary

Villus (VIL-lus): A small, fingerlike projection of the small intestinal wall that contains con- nective tissue, blood vessels, and a lymphatic vessel, and which functions in the absorption of nutrients. Plural form is villi. Visceral (VIS-er-al): Pertaining to the internal components (mainly the organs) of a body cavity; pertaining to the outer surface of an internal organ. Visceral peritoneum (par’-i-to-NE-um): A serous membrane that covers the surfaces of abdom- inal organs. Visceral pleura (PLOO-ra): A serous membrane that covers the outer surface of each lung. Vitreous humor (VI-tre-us HYOO-mer): A mass of gelatinous material located within the eye- ball in the posterior cavity located between the lens and the retina. Also called vitreous body. Vocal cords (VO-kal kordz): Folds of mucous membrane within the larynx that produce sound when they vibrate. Vulva (VUL-va): The external genitalia of the female reproductive system. Also called pudendum.

W

White matter: A type of nerve tissue composed mainly of the myelinated axons of neurons.

Y

Yellow marrow: A collection of fat storage (adi- pose) and other tissues found within the medullary cavities of bones.

Z

Zygote (ZI-got): The single, fertilized cell result- ing from the union of an oocyte with a sperm cell. Zymogenic (zi’-mo-GEN-ik) cell: A cell within a gastric gland of the stomach mucosa that secretes a precursor protein, pepsinogen.