Learning Objectives with Rationale

Instructor’s Manual for 1 4 The Respiratory SystemLEARNING OBJECTIVES WITH RATIONALE After completing this chapter the student will be able to: 1. Discuss the generalized functions of the respiratory system. The organs of the respiratory system are designed to perform two basic functions: (1) they serve as an air distributor, and (2) they serve as a gas exchanger for the body. This system also effectively (1) filters, (2) warms, and (3) humidifies the air we breathe. Sinuses influence sound production and the nose makes the sense of smell possible. The process of respiration is an important homeostatic mechanism. 2. List the major organs of the respiratory system and describe the function of each. a. Nose—Air enters the respiratory tract through the external nares or nostrils. The surface of the nasal cavities is lined with respiratory mucosa kept moist from mucus and warm from blood flowing just under it. As air passes through this area it is humidified and warmed. Nerve endings responsible for smell are located in the nasal mucosa. b. Pharynx—This area is divided into three portions. The uppermost part behind the nasal cavities is the nasopharynx. The portion behind the mouth is called the oropharynx. The lowest segment is called the laryngopharynx. Air and food pass through the pharynx or throat on their way to the lungs and stomach, respectively. Two small masses of lymphatic tissue called pharyngeal tonsils (adenoids) are embedded in the mucous membrane of the pharynx. The auditory, or eustachian tubes, open into the nasopharynx to equalize air pressure between the middle ear and the environment. c. Larynx—Sometimes called the voicebox, this structure is responsible for creating sound. It is covered with a piece of cartilage called the epiglottis, which closes like a trapdoor over the larynx during swallowing and prevents food from entering the trachea. d. Trachea—This tube, often called the windpipe, furnishes part of the open passageway through which air can reach the lungs from the outside. The trachea is lined by the typical respiratory mucosa which contains numerous mucus-producing glands and is covered by cilia. These glands produce mucus that is moved by the beating cilia in one direction to trap and eliminate airborne contaminants. e. Bronchi—These subdivisions of the trachea lead to the lungs. In each lung they branch into smaller, or secondary, bronchi, which branch into bronchioles. Bronchioles subdivide into microscopic tubes called alveolar ducts. Each alveolar duct ends in several grapelike clusters called alveolar sacs. The wall of each alveolar sac is made up of extremely thin-walled structures called alveoli. Alveoli are lined with blood capillaries, so on their surface an exchange of gases between air and blood can take place. The surface of the respiratory membrane inside each alveolus is covered by a substance called surfactant which reduces surface tension in the alveoli and keeps them from collapsing as air moves in and out during respiration. f. Lungs—These two fairly large organs provide an area where air and blood can come close enough to each other for oxygen to move out of the air into blood while carbon dioxide moves out of the blood into air. g. Pleura – The parietal pleura lines the walls of the thoracic cavity. The visceral pleura covers the lungs. The intrapleural space between these two pleural membranes contains fluid to enable the lungs to expand and deflate with each breath. 3. Compare, contrast, and explain the mechanism responsible for the exchange of gases that occurs during internal and external respiration. In breathing, nerve impulses stimulate the diaphragm to contract. Its domelike shape flattens out as it moves down toward the abdominal cavity. This makes the chest cavity longer from top to bottom. Other muscle contractions raise the rib cage to make the chest cavity wider and greater in depth from front to back. As the chest cavity enlarges, the lungs expand along with it and air rushes into them and down into the alveoli. This phase of respiration is called inspiration. For expiration to take place, S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 2 C hapter 14  The Re spira tory S ystem the diaphragm and other respiratory muscles relax, making the chest cavity smaller, thereby squeezing air out of the lungs. Changes in shape and size of the thoracic cavity result in changes in air pressure within the cavity and within the lungs. It is the difference in air pressure that causes movement of air into and out of the lungs. External respiration, the exchange of gases between the blood and the alveolar air, occurs by diffusion. Diffusion is a passive process when gases move from an area of high concentration to an area of lower concentration. The amount of oxygen in the blood is less than the amount in the inspired air. Oxygen diffuses from an area of higher concentration (air in the alveoli) to an area of lower concentration (capillary blood). The diffusion of carbon dioxide happens in the same way down a pressure gradient. The concentration of carbon dioxide in the capillary blood is higher than in the alveolar air. Then the carbon dioxide leaves the body in the next expiration. The exchange of gases between blood and body cells is called internal respiration. The movement of oxygen and carbon dioxide is in the opposite direction as in external respiration. The concentration of oxygen in the cells is lower than that in the oxygenated blood. Oxygen moves out of the blood through the thin capillary walls into the interstitial fluid and on into each cell. Carbon dioxide concentration is higher in the cells and lower in the capillary blood. Again, the gas moves down a pressure gradient out of the cell and into the blood. The carbon dioxide is transported to the lungs for removal in external respiration. 4. List and discuss the volumes of air exchanged during pulmonary ventilation. A spirometer is used to measure the amount of air exchanged in breathing. About 500 milliliters of air is taken into the lungs with each normal inspiration. This amount is called tidal volume. The largest amount of air to breathe in and out in one inspiration and expiration is known as the vital capacity. The normal value of vital capacity is about 4800 milliliters. Expiratory reserve volume is the amount of air that can be forcibly exhaled after expiring the tidal volume. Inspiratory reserve volume is the amount of air that can be forcibly inspired over and above a normal inspiration. As tidal volume increases, both expiratory reserve volume and inspiratory reserve volume will decrease. Vital capacity can be calculated by adding together tidal volume, inspiratory reserve volume, and expiratory reserve volume. Residual volume is the air that remains in the lungs after the most forceful expiration. 5. Identify and discuss the mechanisms that regulate respiration. Respiration depends on proper functioning of respiratory muscles. These muscles are stimulated by nervous impulses that originate in the respiratory control centers that are located in the medulla and pons of the brain. In the medulla the two most important control centers are called the inspiratory center and the expiratory center. The respiratory control centers in the brainstem control the rate and depth of breathing. In addition, the brainstem receives input from other parts of the body, such as information from chemoreceptors and stretch receptors, which can alter breathing patterns. Emotions and sensory input stimuli can also affect respiration. The cerebral cortex can influence respiratory patterns. This voluntary control has limits. Factors such as blood level of carbon dioxide are more powerful in controlling respiration than conscious control. Breathing occurs when the body senses the need for more oxygen or if carbon dioxide levels increase to certain levels. The respiratory system is important in maintaining homeostasis.S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______LECTURE OUTLINE INSTRUCTOR'S NOTESI. STRUCTURAL PLAN (Figure 14-1) Basic plan of respiratory system would be similar to an inverted tree if it were hollow. The trunk of the tree would be the trachea, the bronchi would be the branches, and the leaves would be comparable to alveoli, the microscopic sacs enclosed by networks of capillaries.II. RESPIRATORY TRACTS A. Upper respiratory tract—nose, pharynx, and larynx B. Lower respiratory tract—trachea, all segments of the bronchial tree, lungsIII. RESPIRATORY MUCOSA (Figure 14-2) A. Specialized membrane that lines the air distribution tubes in the respiratory tree B. Over 125 ml of mucus produced each day forms a “mucous blanket” over much of the respiratory mucosa C. Mucus serves as an air purification mechanism by trapping inspired irritants such as dust and pollen D. Cilia on mucosal cells beat in only one direction, moving mucus upward to pharynx for removalIV. NOSE A. Structure 1. External nares, or nostrils, are the entrance for air into the respiratory tract 2. Nasal septum separates interior of nose into two cavities 3. Mucous membrane lines nose 4. Frontal, maxillary, sphenoidal, and ethmoidal sinuses drain into nose (Figure 14-3) 5. Conchae greatly increase the surface over which the air flows as it passes through the nasal cavity B. Functions 1. Warms and moistens inhaled air as it flows over the conchae 2. Contains sense organs of smellV. PHARYNX A. Structure (Figure 14-4) 1. Pharynx (throat) about 12.5 cm (5 inches) long 2. Divided into nasopharynx, oropharynx, and laryngopharynx 3. Two nasal cavities, mouth, esophagus, larynx, and auditory tubes all have openings into pharynx 4. Pharyngeal tonsils and openings of auditory tubes open into nasopharynx; palatine tonsils found in oropharynx 5. Mucous membrane lines pharynxS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 4 C hapter 14  The Re spira tory S ystem LECTURE OUTLINE INSTRUCTOR'S NOTES B. Functions 1. Passageway for food and liquids 2. Air distribution; passageway for airVI. LARYNX A. Structure (Figure 14-5) 1. Several pieces of cartilage form framework a. Thyroid cartilage (Adam’s apple) is largest b. Epiglottis partially covers opening into larynx; acts like a trapdoor to close the larynx during swallowing to prevent food from entering trachea 2. Mucous lining 3. Vocal cords (two fibrous bands) stretch across interior of larynx B. Functions 1. Air distribution; passageway for air to move to and from lungs 2. Voice production—muscles attached to the larynx cartilages pull on the fibrous cords to make them tense (high-pitched sound) or relaxed (low-pitched sound)VII. TRACHEA A. Structure (Figure 14-6) 1. Tube about 11 cm (4 1/2 inches) long that extends from larynx to the bronchi in the thoracic cavity 2. Mucous lining 3. C-shaped rings of cartilage hold trachea open B. Function—passageway for air to move to and from lungs C. Obstruction 1. Blockage of trachea occludes the airway and if complete causes death in minutes 2. Tracheal obstruction causes over 4000 deaths annually in the United States 3. Heimlich maneuver (p. 384) is a lifesaving technique used to free the trachea from obstructionsVIII. BRONCHI, BRONCHIOLES, AND ALVEOLI A. Structure 1. Trachea branches into right and left bronchi 2. Each bronchus branches into smaller and smaller tubes eventually leading to bronchioles 3. Bronchioles end in clusters of microscopic alveolar sacs, the walls of which are made up of alveoli (Figure 14-7) B. Function 1. Bronchi and bronchioles—air distribution; passageway for air to move to and from alveoli 2. Alveoli—exchange of gases between air and blood through the respiratory membrane (Figure 14-8). Surfactant covers the respiratory membrane inside each S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______LECTURE OUTLINE INSTRUCTOR'S NOTES alveolus.IX. LUNGS AND PLEURA A. Structure (Figure 14-10) 1. Size—large enough to fill the chest cavity, except for middle space (mediastinum) occupied by heart and large blood vessels 2. Apex—narrow upper part of each lung, under collarbone 3. Base—broad lower part of each lung; rests on diaphragm 4. Pleura—moist, smooth, slippery membrane that lines chest cavity (parietal pleura) and covers outer surface of lungs (visceral pleura); reduces friction between the lungs and chest wall during breathing (Figure 14- 10) B. Function—breathing (pulmonary ventilation)X. RESPIRATION A. Mechanics of breathing (Figure 14-11) 1. Pulmonary ventilation includes two phases called inspiration (movement of air into lungs) and expiration (movement of air out of lungs) 2. Changes in size and shape of thorax cause changes in air pressure within that cavity and in the lungs 3. Air pressure differences actually cause air to move into and out of the lungs B. Inspiration 1. Active process—air moves into lungs 2. Inspiratory muscles include diaphragm and external intercostals a. Diaphragm flattens during inspiration— increases top to bottom length of thorax b. External intercostals’ contraction elevates the ribs and increases the size of the thorax from the front to the back and from side to side 3. The increase in the size of the chest cavity reduces pressure within it, and air enters the lungs C. Expiration 1. Quiet expiration is ordinarily a passive process 2. During expiration, thorax returns to its resting size and shape by relaxation of the diaphragm and intercostal muscles 3. Elastic recoil of lung tissues aids in expiration 4. Expiratory muscles used in forceful expiration are internal intercostals and abdominal muscles a. Internal intercostals—contraction depresses the rib cage and decreases the size of the thorax from the front to back b. Contraction of abdominal muscles S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 6 C hapter 14  The Re spira tory S ystem LECTURE OUTLINE INSTRUCTOR'S NOTES elevates the diaphragm, thus decreasing size of the thoracic cavity from the top to bottom 5. Reduction in the size of the thoracic cavity increases its pressure and air leaves the lungs D. Exchange of gases in lungs (Figure 14-12) 1. Carbaminohemoglobin breaks down into carbon dioxide and hemoglobin 2. Carbon dioxide moves out of lung capillary blood into alveolar air and out of body in expired air 3. Oxygen moves from alveoli into lung capillaries 4. Hemoglobin combines with oxygen, producing oxyhemoglobin E. Exchange of gases in tissues 1. Oxyhemoglobin breaks down into oxygen and hemoglobin 2. Oxygen moves out of tissue capillary blood into tissue cells 3. Carbon dioxide moves from tissue cells into tissue capillary blood 4. Hemoglobin combines with carbon dioxide, forming carbaminohemoglobin F. Volumes of air exchanged in pulmonary ventilation (Figure 14-13) 1. Volumes of air exchanged in breathing can be measured with a spirometer 2. Tidal volume (TV)—amount normally breathed in or out with each breath 3. Vital capacity (VC)—largest amount of air that one can breathe out in one expiration 4. Expiratory reserve volume (ERV)— amount of air that can be forcibly exhaled after expiring the tidal volume 5. Inspiratory reserve volume (IRV)— amount of air that can be forcibly inhaled after a normal inspiration 6. Residual volume (RV)—air that remains in the lungs after the most forceful expiration 7. Rate—usually about 12–18 breaths a minute; much faster during exercise G. Regulation of respiration (Figure 14-14) 1. Regulation of respiration permits the body to adjust to varying demands for oxygen supply and carbon dioxide removal 2. Most important central regulatory centers in medulla are called respiratory control centers (inspiratory and expiratory centers) a. Under resting conditions, nervous activity in the respiratory control centers produces a normal rate and depth of respirations (12–18 per minute) 3. Respiratory control centers in the medulla are influenced by “inputs” from receptors located in other body areas: a. Cerebral cortex—voluntary (but limited) control of respiratory activityS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______LECTURE OUTLINE INSTRUCTOR'S NOTES b. Chemoreceptors respond to changes in carbon dioxide, oxygen, and blood acid levels—located in carotid and aortic bodies c. Pulmonary stretch receptors—respond to the stretch in lungs, thus protecting respiratory organs from overinflationXI. TYPES OF BREATHING A. Eupnea—normal breathing B. Hyperventilation—rapid and deep respirations C. Hypoventilation—slow and shallow respirations D. Dyspnea—labored or difficult respirations E. Apnea—no respirations F. Respiratory arrest—failure to resume breathing after a period of apneaCLASSROOM APPLICATION The following questions can be used as individual assignments or for small-group discussion. Note: to copy the questions, cover the answers with a blank sheet of paper and print, thus leaving space for answers or note-taking. 1. Explain and describe the mechanics of respiratory effort during inspiration and expiration. Answer: Mechanics of breathing: During inspiration, the diaphragm contracts, increasing the volume of the thoracic cavity. This increase in volume results in a decrease in pressure, which causes air to rush into the lungs. During expiration, the diaphragm returns to an upward position, reducing the volume in the thoracic cavity. Air pressure increases, forcing air out of the lungs. 2. Some industrial pollutants can accidentally cause respiratory distress syndrome (RDS) in workers near the source of pollution. Such pollutants normally destroy or inhibit a chemical normally found in the lungs. What is this lung chemical? (Hint: Read the section entitled Bronchi, Bronchioles, and Alveoli) Answer: Surfactant is a special chemical in the fluid lining the lungs that prevents collapse of the alveoli. Lack of this chemical in infants causes infant respiratory distress syndrome because the alveoli keep collapsing, and it requires great effort to reinflate them without surfactant. Some chemicals used in industry, when breathed in large enough quantities, can destroy or overcome the function of surfactant and thereby cause respiratory distress (great difficulty in breathing) in adults. 3. Someone you know has vomited while in an alcohol-induced sleep and now seems to be having great difficulty breathing. What do you suppose has caused this? (Hint: Think about the information from part 1. Is this person also in respiratory distress? Look at Figure 14-5 for some information regarding the structural possibilities. Alcohol and some other drugs often inhibit protective reflexes.) Answer: Vomiting is a common consequence of overconsumption of alcohol. Alcohol may also inhibit normal muscular reflexes that protect us from aspirating (breathing in) vomit or other materials that pass by the opening of the lower respiratory tract. Probably as vomiting occurred, some material slipped under the lip of the epiglottis and then past the vocal folds (cords) and into the bronchial tree. The material may have damaged the surfactant, causing respiratory distress as in #2 above, or chunks of material may have actually blocked parts of the bronchial tree, also causing respiratory distress. This may be a life-threatening situation.LAB ACTIVITIESS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 8 C hapter 14  The Re spira tory S ystem 1. Arrange for students to visit the respiratory department of a local hospital and observe clients receiving respiratory treatment. 2. Provide students with portable spirometers and allow them to determine tidal volume, expiratory reserve volume, inspiratory reserve volume, and vital capacity. 3. Provide students with stethoscopes so that they can listen to bronchial sounds during both inspiration and expiration. 4. Have students examine prepared slides under the microscope that show lung cancer and emphysema. 5. From a local hospital, obtain spirograms of people who suffer from disorders of the respiratory system. Provide an opportunity for students to study these. 6. Visit a local hospital’s department of respiratory therapy. Ask the therapist to demonstrate for the students various methods of oxygen administration. 7. Have a respiratory therapist demonstrate the use of pulse oximetry and have the students practice assessing arterial blood saturation on each other with oximetry.PRACTICAL/CREATIVE LEARNING ACTIVITIES 1. Ask a member of the Cystic Fibrosis Foundation to talk with the students concerning how this disease affects an individual’s physical, mental, and social well-being. 2. With the use of a spirometer compare the lung capacity of the following: a person who smokes, a nonsmoker, an infant, a 7-year-old, a sedentary individual, an athlete, and an older adult. 3. Have students define hyperventilation and explain why breathing into a paper bag restores normal blood chemistry more rapidly than continued breathing into the atmosphere. 4. Mr. Hallows, unconscious and not breathing, is receiving pulmonary resuscitation. In this situation should 100% oxygen be given or a mixture of oxygen and carbon dioxide? Discuss and explain your answer in class with other students. 5. Provide students with current information from the American Lung Association regarding the hazards of smoking. 6. Arrange a visit from your local Red Cross unit to teach CPR and the Heimlich maneuver to students. These techniques, when taught and used with skill, can be life-saving in an emergency. In recent years there have been some changes in the procedures so a licensed CPR instructor is a must.S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______ANSWERS TO CHAPTER 14 TEXTBOOK QUESTIONSReview Questions 1. Differentiate between the respiratory membrane and the respiratory mucosa. Answer: Respiratory membrane is the single layer of cells that makes up the wall of the alveoli. Respiratory mucosa is the mucus-covered membrane that lines the tubes of the respiratory tree. 2. List the functions of the paranasal sinuses. Answer: The four paranasal sinuses are frontal, maxillary, sphenoidal, and ethmoidal. They drain into the nasal cavities and are lined with mucous membranes that assist in the production of mucus for the respiratory tract and serve as resonant chambers for sound. 3. What is the function of the auditory tube? Answer: The auditory or eustachian tubes open into the nasopharynx and connect with the middle ear. This connection permits equalization of air pressure between the middle and the exterior ear. 4. What is the function of the epiglottis? Answer: The epiglottis is a lidlike cartilage overhanging the entrance to the larynx. It closes off the larynx during swallowing, which prevents food from entering the trachea. 5. Describe, in decreasing order of size, the structures that make up the air tubes of the lung. Answer: The trachea branches into the right and left bronchi. Each bronchus branches into smaller and smaller tubes leading to bronchioles. The bronchioles end in clusters of microscopic alveolar sacs, the walls of which are made up of alveoli. 6. Describe pleura. What is the function of pleural fluid? Answer: The pleura is a moist, smooth, slippery membrane that lines the chest cavity and covers the outer surface of the lungs. A separate pleural sac encases each lung. The outer surface of each lung is covered by the visceral layer of the pleura. The visceral pleura lies against the parietal pleura, separated only by the pleural space, which contains just enough pleural fluid for lubrication to prevent friction during respiration. 7. Differentiate among external respiration, internal respiration, and cellular respiration. Answer: External respiration is the exchange of gases between air in the lungs and in the blood. Internal respiration is the exchange of gases between the blood and the cells of the body. Cellular respiration refers to the actual use of oxygen by the cells in the process of metabolism. 8. Explain the mechanical process of inspiration. Answer: Inspiration is the active process of air moving into the lungs. The muscles of inspiration include the diaphragm and the external intercostals. As the diaphragm flattens during inspiration, the external intercostals contract, thereby elevating the ribs and increasing the size of the thorax. The increase in the size of the chest cavity reduces the pressure, which allows air to enter the lungs. 9. Explain the mechanical process of expiration. Answer: Expiration is most often a passive process. During expiration, the thorax returns to its resting size and shape. The expiratory muscles used in forceful expiration are the internal intercostals and the abdominal muscles. The internal intercostals contract, depressing the rib cage and decreasing the size of the thoracic cavity. The abdominal muscles contract, elevating the diaphragm, which also decreases the size of the thoracic cavity. Reduction in the size of the thoracic cavity increases pressure and air leaves the lungs.10. Define the term “partial pressure” (P) of a gas and explain how the partial pressure of oxygen (PO2) and carbon dioxide (PCO2) influence their diffusionS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 10 C hapter 14  The Re spira tory S ystem Answer: The definition of partial pressure (law of partial pressure) is the pressure exerted by any one gas in a mixture of gases or in a liquid. According to this law (Dalton’s law), the partial pressure of gases is directly related to the concentration of that gas in the mixture and to the total pressure of the mixture. The relationship of this law and the exchange of oxygen and carbon dioxide in the lungs is as follows: The exchange of gases in the lungs (respiratory membrane) takes place between alveolar air and the blood in the capillaries surrounding each alveolus. Gases will move in both directions. Oxygen will move from the alveolus because the PO2 of alveolar air is greater than the PO2 of the capillaries. Carbon dioxide will move from the capillaries by diffusing into the alveolus. The PCO2 of the venous blood is much higher than the PCO2 in the alveolus. Thus, both gases move down a “pressure gradient.” As in diffusion, these molecules (O2, CO2) move from areas of high concentration to areas of low concentration. 11. Explain how gas is exchanged between the lung and the blood, and between the blood and the tissues. Answer: The exchange of gases in lung tissue occurs when carbaminohemoglobin breaks down into carbon dioxide and hemoglobin. Carbon dioxide moves out of lung capillary blood into alveolar air and out of the body in expired air. Oxygen moves from the alveoli into the capillaries of the lungs. Hemoglobin then combines with oxygen, producing oxyhemoglobin. The exchange of gases in tissue occurs when oxyhemoglobin breaks down into oxygen and hemoglobin. Oxygen then moves out of tissue capillary blood into tissue cells. Carbon dioxide moves from tissue cells into tissue capillary blood. Hemoglobin combines with carbon dioxide to form carbaminohemoglobin. 12. How is oxygen carried in the blood? How is carbon dioxide carried in the blood? Answer: Oxygen combines with hemoglobin (Hb) in the form of oxyhemoglobin. Carbon dioxide is carried as bicarbonate ion (HCO3) in the blood. 13. Name and explain the volumes that make up vital capacity. Answer: Vital capacity is the largest amount of air that can be moved into and out of the lungs in one inspiration and expiration. Expiratory reserve volume (ERV) is the amount of air that can be forcibly exhaled after a normal inspiration. Inspiratory reserve volume (IRV) is the amount of air that can be forcibly inhaled after a normal inspiration. Residual volume (RV) is the amount of air that remains in the lungs after forceful expiration. 14. Explain the function of chemoreceptors in regulating respiration. Answer: Chemoreceptors are located in the carotid and aortic bodies. They are specialized receptors that are sensitive to the increase in carbon dioxide and acid levels in the blood as well as the decrease in blood oxygen levels. When stimulated, the chemosensitive cells send nerve impulses to the respiratory regulator centers that modify respirations. 15. Explain the function of stretch receptors in the lungs. Answer: Stretch receptors are located in the pulmonary airways and in the alveoli of the lungs. These receptors generate nerve impulses that influence normal breathing and protect the respiratory system from excess stretching which could cause damage with overinflation.Critical Thinking Questions 16. Explain the effect smoking has on the body’s ability to remove trapped material in the respiratory mucosa. Answer: The microscopic cilia that cover epithelial cells in the respiratory mucosa move in one direction only. The result is movement of mucus toward the pharynx. Cigarette smoke paralyzes these cilia and results in accumulations of mucus and a smoker’s cough, which is an effort to clear the secretions. 17. The developing fetus does not produce lung surfactant until late in its development. Explain what problem a premature infant would have if it were born before it had produced surfactant.S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______Answer: Surfactant is manufactured by specialized cells in the walls of the alveoli. Surfactant reduces the surface tension of the fluid on the surface of the alveolar walls and permits easy movement of air into and out of the lungs. The ability of the body to manufacture surfactant is not fully developed until shortly before birth, about 40 weeks gestation. A premature infant of less than 37 weeks would have difficulty reinflating collapsed alveoli and would develop symptoms of respiratory distress and very likely would not live without treatment. 18. Explain the role of other systems in the regulation of respiration. Answer: The most important central regulator centers are in the medulla; they are called the respiratory control centers. Under resting conditions, nervous activity in the respiratory control centers produces a normal rate and depth of 12–18 breaths per minute. The cerebral cortex has limited voluntary control of respiratory activity. Chemoreceptors respond to changes in carbon dioxide, oxygen, and blood acid levels located in the carotid and aortic bodies. Pulmonary stretch receptors respond to the stretch in lungs, thus protecting respiratory organs from overinflation.S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 12 C hapter 14  The Re spira tory S ystem Instructor’s Manual for 1 4 The Respiratory SystemSTUDENT ASSIGNMENTMatching Select the most appropriate answer from Column B for each item in Column A. (Only one answer is correct for each.)Column A Column B _____ 1. Vocal cords A. Serous membrane _____ 2. Pulmonary ventilation B. Pharynx _____ 3. Pleura C. Mucus _____ 4. Pneumothorax D. Chemoreceptor _____ 5. Aortic body E. Larynx _____ 6. Throat F. Diffusion _____ 7. Respiratory mucosa G. Collapsed lung _____ 8. Windpipe H. Trachea _____ 9. Alveoli I. Breathing _____ 10. Surfactant J. Surface tensionMultiple Choice 11. Chemoreceptors in the carotid and aortic bodies are characterized by which of the following? A. Sensitive to increase in blood carbon dioxide levels B. Found in the brain C. Sensitive to increases in blood oxygen levels D. Send impulses to the heart 12. What is the lowest segment of the pharynx called? A. oropharynx B. laryngopharynx C. nasopharynx D. hypopharynx 13. What is the narrow upper portion of a lung called? A. base B. notch C. costal surface D. apex 14. What is the largest amount of air that we can breathe in and out in one inspiration and expiration called? A. tidal volume B. vital capacity C. residual volume D. inspiratory reserve volumeS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______15. Which of the following statements, if any, is not characteristic of human lungs? A. Both right and left lungs are composed of three lobes. B. Bronchi subdivide to form bronchioles. C. Capillary supply is abundant to facilitate gas exchange. D. All of the above statements are characteristic of human lungs. 16. Which of the following body functions is made possible by the existence of fibrous bands stretched across the larynx? A. swallowing B. breathing C. diffusion D. speech 17. The walls of the trachea are made more rigid by the presence of which of the following? A. rings of cartilage B. thyroid cartilage C. epiglottis D. vocal cords 18. Which of the following is true of the exchange of respiratory gases between lungs and blood? A. It takes place by diffusion. B. It is called external respiration. C. Both A and B is true. D. None of the above is true. 19. When the diaphragm contracts, which phase of ventilation is taking place? A. External respiration B. Expiration C. Internal respiration D. Inspiration 20. Which of the following is not characteristic of the nasal cavities? A. They contain many blood vessels that warm incoming air. B. They contain the adenoids. C. They are lined with mucous membranes. D. They are separated by a partition called the nasal septum.Completion Complete the following statements using the terms listed below. A. Glottis G. Residual volume B. Heimlich maneuver H. Respiratory membrane C. Tonsils I. Epiglottis D. Primary bronchi J. Internal respiration E. Medulla K. Sinuses F. Spirometer L. Ventilation 21. The exchange of gases that occurs between the blood and the cells of the body is called _____. 22. A device used to measure the amount of air exchanged in breathing is called a(n) _____. 23. A structure called the _____ exists as a thin barrier between blood in the capillaries and air in the alveolus. 24. Structures called _____ produce mucus for the respiratory tract, help lighten the skull bones, and serve as resonant chambers for the production of sound.S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 14 C hapter 14  The Re spira tory S ystem 25. An effective and often life-saving technique that can be used to open a windpipe that is suddenly obstructed is called the _____. 26. The inspiratory center and the expiratory center are located in the _____. 27. The air that remains in the lungs even after the most forceful expiration is called _____. 28. The space between the vocal cords is called the _____. 29. Masses of lymphatic tissue called _____ are embedded in the mucous membrane of the pharynx. 30. When the trachea subdivides to enter both lungs, the tubes that are thereby formed are called _____.Multiple ChoiceVicki, a 31-year-old secretary, is up for a promotion that she is very excited about. This morning she will be interviewed for the position. As she waits outside her boss’s office, she begins to breathe rapidly and feels dizzy. 31. From your knowledge of the respiratory system, you know Vicki is experiencing which of the following? A. an attack of bronchitis B. hypoxia C. pneumothorax D. hyperventilation 32. Normal respiration rate range for an adult is between which of the following? A. 12–18 breaths/minute B. 20–24 breaths/minute C. 7–12 breaths/minute D. 24–30 breaths/minute 33. Vicki noticed there were other times she had difficulty breathing. After visiting her doctor he told her she had small growths called polyps that were situated between the small lateral projections on the walls of her nasal cavities. What are these projections called? A. alveolars B. sphincters C. conchae D. parotid glands 34. Vicki’s son, Chad, often complains of severe headaches and soreness around his nose and above his eyebrows. The pediatrician examines Chad and says that he has an infection of the air spaces within the cranial bones. What are these called? A. cilia B. parietal bones C. foramen D. sinusesS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______Identification Label the following areas of face and neck. Write your answers on the blanks provided. 35. Sagittal View of Face and Neck (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (15) (16) (17) (18) (19) (20) (21) (22) (23)S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton 16 C hapter 14  The Re spira tory S ystem Identification 36. Identify the structural plan of the respiratory organs. (a) Lower respiratory tract______(b) Oropharynx______(c) Larynx______(d) Alveoli______(e) Nasal cavity______(f) Alveolar duct______(g) Pharynx______(h) Upper respiratory tract______(i) Laryngopharynx______(j) Bronchioles______(k) Alveolar sac______(l) Trachea______(m) Nasopharynx______(n) Capillary______S t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton ______ANSWERS TO CHAPTER 14 STUDENT ASSIGNMENTMatching 1. E Multiple Choice 2. I 31. D 3. A 32. A 4. G 33. C 5. D 34. D 6. B 7. C Identification 8. H 35. (1) Sphenoidal air sinus; (2) pharyngeal 9. E tonsil (adenoids); (3) nasopharynx; (4) 10. J uvula; (5) palatine tonsil; (6) oropharynx; (7) epiglottis; (8) laryngopharynx; (9) Multiple Choice esophagus; (10) trachea; (11) vocal cords; 11. A (12) thyroid cartilage (part of larynx); (13) 12. B lingual tonsil; (14) hyoid bone; (15) soft 13. D palate; (16) tongue; (17) hard palate; (18) 14. B inferior concha; (19) middle concha; (20) 15. A nasal bone; (21) frontal air sinus; (22) 16. D superior concha; (23) opening of auditory 17. A (eustachian) tube 18. C 36. (a) 2; (b) 7; (c) 5; (d) 11; (e) 10; (f) 12; (g) 9; 19. D (h) 1; (i) 6; (j) 3; (k) 13; (l) 4; (m) 8; (n) 14 20. BCompletion 21. J 22. F 23. H 24. K 25. B 26. E 27. G 28. A 29. C 30. DS t ruct ure & Funct io n of t he B ody, 14th ed. C o pyrig ht © 2012 by Elsev ier I nc. A llr ights reserved. T h ibod eau & P atton

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