Digestive System (Pp. 75 89 in the Rat Dissection Guide)

Name ______

RAT DISSECTION PACKET

Use your outlines and the Rat Dissection Guide to fill in the information about each of the following structures in the rat. Be concise (complete sentences are not required), but also be sure to include all important info! You Rat Practical Exam will include questions about functions, secretions, tissue types, etc. This is your preparation guide for the practical exam. All questions are taken from this packet!

Digestive System – (pp. 75 – 89 in the Rat Dissection Guide) Structure Function/Characteristics - Includes mouth, salivary glands, teeth, & tongue Oral Cavity - Mechanical digestion of carbs, lipids, proteins, & nucleic acids takes place here - Chemical digestion of starch occurs through the action of salivary amylase - Saliva also helps moisten food for easier swallowing; contains an anti-bacterial agent to help fight off microbes - chewed up food is known as a bolus

Digastricus - depresses or lowers the mandible Muscles - made of skeletal muscle tissue (see pp. 39, 56)

Masseter Muscles - elevates or raises the mandible (see pp. 42, 56)

Salivary Glands - secrete enzyme amylase to chemically break down starch (carbohydrate) - saliva moistens food so swallowing is easier - secrete other enzymes that destroy pathogens

- soft, muscular tube that carries food from the pharynx to the stomach Esophagus - contains a cardiac sphincter between it and the stomach - bolus moves down through smooth muscle contractions called peristalsis - NO digestion occurs here

- Thick walled, muscular sac that churns (peristalsis) to mechanically break down all Stomach macromolecules even further - Secretes HCl and pepsin for the chemical breakdown of PROTEINS. - Lined with mucus to protect itself from the highly acidic contents known as chyme

- Most chemical digestion occurs here Small Intestine - Na+ bicarbonate from the pancreas enters here to neutralize the acidic chyme from the Duodenum – stomach - Bile from the liver enters here to MECHANICALLY break down fats - Digestive enzymes (amylase, lipase, trypsin) complete the chemical breakdown of carbs, Jejunum & lipids, proteins Ileum ------Contain villi for nutrient absorption - Each villi contains a capillary network through which the nutrients diffuse through to get into the bloodstream

Large Intestine Caecum – first part of the large intestine; absorbs excess H2O from the waste (locate caecum & rectum) Rectum – last portion of the alimentary canal; eliminates undigestible material (cellulose from plant material); Contains 2 sphincters

Urinary System – (pp. 117 – 118) Structure Function/Characteristics

Kidney - Paired organs on dorsal side of rat on either side of the spinal cord - Contain millions of nephrons (filtering unit of the kidney) - Function is to remove urea from the blood; urea comes from the breakdown of proteins.

Ureter - tubes that carry urine (urea and water) from the kidneys to the urinary bladder - smooth muscle contractions move the urine along

Urinary Bladder - muscular sac that collects and stores urine until it is expelled from the body

Urethra - exit through which urine leaves the body

Miscellaneous Organs – (pp. 79, 81, 87, 88, 113) Structure System Function/Characteristics 1. secretes bile into the duodenum for the mechanical breakdown of fats Digestive Liver 2. maintains constant blood glucose concentration by storing excess glucose as glycogen or breaking down glycogen into glucose when we need it.

3. detoxifies drugs, alcohol, and poisons

Pancreas 1. Digestive 1. produces Na+ bicarbonate to neutralize acidic chyme in the duodenum; produces digestive enzymes to complete the chemical breakdown of all macromolecules in the duodenum. 2. Endocrine 2. secretes hormones to help regulate blood sugar levels: insulin when blood sugar levels are high; glucagon when blood sugar levels are low

Spleen Lymphatic - Produces WBC’s that aid in immunity - removes old and worn out RBC’s

Thymas 1. Lymphatic 1. produces lymphocytes to aid in immunity 2. Endocrine 2. produces hormones to stimulate T-cell production (immunity)

Adrenal glands Endocrine - Located on top of each kidney - secretes epinephrine which is the fight or flight hormone that gives the rat “super rat strength” In life threatening situations.

Reproductive Systems – (pp. 118 – 128) Structure Function/Characteristics

Scrotum/ Scrotum – sac that contains and protects the testes Testes Testes – produce sperm and the hormone testosterone

Vesicular glands Large glands that add fluid to the sperm to make semen (also called seminal vesicles)

Ovaries Female reproductive structures that produce eggs and the hormones estrogen and progesterone

Uterus Divided into two complete uteri, each of which opens into the vagina Place for the embryos to develop

Vagina Place where the two uteri meet; canal that excretes the eggs

Circulatory & Respiratory Systems – (pp. 91 – 115 in the Rat Dissection Guide ) Structure Function/Characteristics Trachea - Tube that goes from the pharynx to the lungs - Lined with cartilage rings that support it from collapsing - Branches into the bronchi

Bronchi - Branches off of the trachea - Branches further into the bronchioles - Lined with cilia and cells that secrete mucus

Lung - Contains alveoli where the exchange of O2 and CO2 takes place - Surrounded by the pleural membranes - No muscles are directly attached; however, the diaphragm and intercostal muscles aid in breathing

Diaphragm - Dome shaped muscle below the lungs - Helps with inhalation and exhalation - Composed of skeletal muscle - Contracts when the medulla oblongata sends a message for it to contract

Heart Right – upper chamber of the heart that receives deoxygenated blood coming from the body; atria walls are thin and less elastic than the ventricles. Left – upper chamber of the heart that receives oxygenated blood coming from the lungs so that it can be pumped to Ventricles the body; walls are thin and less elastic. ------Right – lower chamber of the heart; more muscular than the atria; pumps deoxygenated blood to the lungs through the pulmonary artery Left - lower chamber of the heart; most muscular chamber; pumps oxygenated blood to the body through the ascending and descending aortas.

Carry oxygen rich blood from the aorta of the heart back into the myocardium of the heart so Coronary arteriesthat the heart has plenty of oxygen and nutrients to carry out cellular respiration.

Superior – receives O2 poor blood coming from the head, neck, upper body; passes it to the Vena cava right atrium

Inferior - receives O2 poor blood coming from the lower body; passes it to the right atrium

Ascending – carries O2 rich blood to the head, neck, upper body; branches into arteries and then Aorta arterioles

Descending – carries O2 rich blood to the parts of the lower body; branches into arteries and arterioles

Additional Questions: The following questions do not need to be answered in complete sentences, but the answers must be complete!

1. Define anterior, posterior, dorsal, and ventral. Anterior – head end Posterior – rear end Dorsal – back Ventral - front

2. To what system does the rat’s hair belong? Integumentary

3. List three types of muscle tissue. Describe the characteristics of each type and give examples of each. 1. Smooth – involuntary, smooth, spindle shaped, arranged in sheets. Ex: digestive tract, lining the blood vessels 2. Cardiac – involuntary, striated, cells are latticed to produce a powerful contraction. Ex: heart 3. Skeletal – voluntary, striated, multinucleated. Ex: biceps, triceps *Medulla sends the message to smooth muscle to contract, cerebrum sends message to skeletal muscle to contract* 4. List the pathway of blood through the rat, beginning with the vena cava. Indicate in which structures and vessels the blood is oxygenated. Superior & inferior vena cavaright atriumright ventriclepulmonary arterylungpulmonary veinleft atriumleft ventricleascending & descending aortabody Oxygenated: pulmonary vein through aorta

5. What bones protect the rat’s heart and lungs? Sternum and costas

6. What accessory organ to digestion is lacking in the rat? Think about the function of this organ in humans. Consider the diet of the rat. Why do you think the rat lacks this accessory organ? Gall bladder; they do not have a diet that is high in fat.

7. Describe the four tissue types. Give an example of each. 1. Epithelial – covers the body, lines the cavities, organs, vessels. Capable of secreting… Ex: skin, thymus gland, salivary gland 2. Connective – most widespread & abundant tissue in the body; used as support, for transport, storage, & connectors. Contains a network of non-living material called a matrix. Ex: blood, bone, cartilage, adipose 3. Muscle – able to generate electrical signals that create force and movement. Ex: skeletal, cardiac, smooth 4. Nerve – specialized to generate electrical signals to transfer information. Ex: brain, spinal cord, nerves

8. What part of the brain is in charge of the endocrine glands of the rat? Hypothalamus

9. What part of the brain is monitoring the need to breathe? What is it monitoring in the blood? What part of the brain sends the stimulus to the diaphragm to contract? Hypothalamus monitors the need to breathe; it is monitoring CO2 concentration in the blood; medulla oblongata sends the stimulus to the Diaphragm to contract.

10. Refer to page 2 in the Rat Dissection Guide. List the scientific classification of the rat to its species level. At what level do rats diverge from humans? Kingdom – Animalia Phylum – Chordata Class – Mammalia Rats diverge from humans at the order level Order – Rodentia Family – Muridae Genus – Rattus Species - norvegicus

11. What teeth are especially prominent in rats and other rodents? Why? Incisors; used for gnawing

12. What position is the trachea to the esophagus? Trachea is ventral to the esophagus; esophagus is dorsal to trachea

13. What features distinguish the trachea from the esophagus? Trachea is lined with cartilage rings