Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 9 Textbook The Respiratory System Chapter-Opening Question Generally, no. During maximal exercise, only about 65% of the vital capacity of your lungs is being used. Because high-intensity exercise does not require 100% of the lungs’ vital capacity, lung volume is not a limiting factor for healthy individuals such as athletes. Lesson 9.1 Functions and Anatomy of the Respiratory System Before You Read Which organs and structures are part of the respiratory system? the nose, pharynx, larynx, trachea, bronchi, bronchioles, and lungs Which structure routes air, foods, and liquids through the proper passageways? the epiglottis Where does gas exchange take place, and why does it happen so effortlessly? Gas exchange occurs in the alveoli. The surface area of the lungs is immense: millions of alveolar sacs provide a nearly unlimited number of sites for gas exchange between the blood and these sacs. Also, oxygen and carbon dioxide molecules have a short distance to travel (from the red blood cell, through the capillary wall and its membrane, and through the alveolar wall and its membrane). Finally, gases always diffuse (spread) from area of high concentration to areas of low concentration. Because carbon dioxide has a high concentration in the capillary blood, it diffuses rapidly from the blood into the alveolar sacs, where the concentration of carbon dioxide is low. Check Your Understanding, page 305 1. the nose, pharynx, larynx, trachea, bronchi, bronchioles, and lungs 2. filtering and removing foreign particles from inspired air; humidifying and controlling the temperature of inspired air; producing sound (voice); providing a sense of smell; conducting air to the lower respiratory tract; aiding in the body’s immune defense 3. the trachea, bronchi, bronchioles, and lungs 4. the nose Check Your Understanding, page 306 1. 2. 3. 4. the nasal cavity and mouth The uvula hangs from the end of the soft palate the respiratory and digestive systems The larynx routes air and food to the proper passageways, and it houses the structures that produce speech. Caption Questions Figure 9.1: the pulmonary system Figure 9.2: Air, food, and liquids pass through the pharynx. The air that reaches the lower respiratory tract is warm, moist, and filtered as a result of the work done by the upper respiratory tract. Figure 9.3: Each sinus is named for the bone on which it lies. Figure 9.4: C-shaped rings; on the anterior side of the trachea, they provide support to prevent the airway from collapsing, and on the posterior side, they are flexible and allow the trachea to expand. Figure 9.5: The surface area of the lungs is immense: millions of alveolar sacs provide a nearly unlimited number of sites for gas exchange between the blood and these sacs. Also, oxygen and carbon dioxide molecules have a short distance to travel (from the red blood cell, through the capillary wall and its membrane, and through the alveolar wall and its membrane). Finally, gases always diffuse (spread) from area of high concentration to areas of low concentration. Because carbon dioxide has a high concentration in the capillary blood, it diffuses rapidly from the blood into the alveolar sacs, where the concentration of carbon dioxide is low. Figure 9.6: The left lung is narrower because it only has only two lobes. Know and Understand 1. to provide a constant supply of oxygen, while eliminating the waste product carbon dioxide from the body 2. The bronchi and bronchioles together are called the conducting zone because they are the passageways that conduct air to and from the lungs. 3. The right lung has three lobes, and the left lung has two lobes. 4. The cilia trap and prevent particles from entering the nose. 5. the roof of the mouth 6. the structures that produce speech 7. cartilaginous rings, or C-shaped rings Analyze and Apply 8. because accumulated mucus has covered the olfactory receptors 9. While in the womb, the parts of the baby’s palate did not completely fuse together; surgery can be performed to close and repair the cleft palate and/or lip. 10. The epiglottis is called the gatekeeper because it controls the destination of ingested food and liquids and of inspired air. 11. Gas exchange occurs so rapidly because the surface area of the lungs is immense: millions of alveolar sacs provide a nearly unlimited number of sites for 1 gas exchange between the blood and these sacs. Also, oxygen and carbon dioxide molecules have a short distance to travel (from the red blood cell, through the capillary wall and its membrane, and through the alveolar wall and its membrane). Finally, gases always diffuse (spread) from area of high concentration to areas of low concentration. Because carbon dioxide has a high concentration in the capillary blood, it diffuses rapidly from the blood into the alveolar sacs, where the concentration of carbon dioxide is low. In the Lab 12. Models will vary, but each major organ and structure should be properly labeled. Lesson 9.2 Respiration: Mechanics and Control Before You Read Which muscles are used for breathing? the external intercostal muscles and the diaphragm muscle How do oxygen and carbon dioxide levels regulate our breathing? High levels of carbon dioxide increase the number of hydrogen ions in the body, which cause the pH of the cerebrospinal fluid to decrease. The central chemoreceptors sense this pH decrease and stimulate the brain’s inspiratory center by sending impulses via the vagus and glossopharyngeal nerves. When the inspiratory center receives these signals, it stimulates an increase in the rate and depth of breathing. The result is a fresh oxygen supply and lower carbon dioxide levels. Check Your Understanding, page 312 1. gas exchange 2. The volume of a gas is inversely proportional to its pressure. 3. lower 4. inspiration Check Your Understanding, page 315 1. 2. 3. 4. 5. neural and chemical factors 12 to 15 breaths per minute between 40 and 60 breaths per minute in the medulla oblongata and the pons The medulla sets the normal breathing pace, and the pons fine-tunes respiratory rate and depth while coordinating the transition between inspiration and expiration. Check Your Understanding, page 316 1. the total amount of air that can be forcibly expired after a maximal inspiration 2. Inspiratory reserve volume is the amount of air that can be inhaled immediately following a normal inspiration. Expiratory reserve volume is the amount of air that can be exhaled immediately following a normal expiration. 3. A pulmonary function test can determine whether an individual has asthma, obstructive lung disease, or restrictive lung disease. Introduction to Anatomy and Physiology Caption Questions Figure 9.7: As the lungs expand, the intrapulmonary pressure falls below the atmospheric pressure, creating a vacuum. The vacuum sucks air into the lungs until the intrapulmonary pressure is equal to the atmospheric pressure. When the intrapulmonary pressure exceeds the atmospheric pressure, air is forced out of the lungs. Figure 9.10: to diagnose lung disorders Know and Understand 1. pulmonary ventilation, external respiration, respiratory gas transport, and internal respiration 2. When dust or another irritant needs to be cleared from the lower respiratory tract, a deep breath closes the epiglottis, and a forceful exhalation is performed to clear the dust or other debris. 3. Women have a smaller lung capacity than men. 4. When you move from a reclined position to a standing position, your breathing rate nearly doubles. 5. in the medulla oblongata and the pons Analyze and Apply 6. The stretch receptors are mechanoreceptors in the bronchioles and alveoli. As the lungs fill with air, the stretch receptors trigger the Hering-Breuer reflex, which prevents overinflation of the alveolar sacs. 7. Boyle’s law states that the volume of a gas is inversely proportional to its pressure; in other words, as the volume of a gas increases, its pressure decreases. Boyle’s law affects breathing because of differences between atmospheric (outside) air pressure and intrapulmonary (lung) air pressure. For the lungs to be able to take in air, the intrapulmonary pressure must be lower than the atmospheric pressure. Likewise, for air to be expelled from the lungs, the intrapulmonary pressure must be higher than the atmospheric pressure. 8. Infants take more breaths each minute than older children and adults because their lung capacity is very small. In the Lab 9. Students’ lung volume measurements will vary. Lesson 9.3 Respiratory Disorders and Diseases Before You Read How common is the common cold? Most people get between two and four colds each year. What is the leading cause of chronic obstructive pulmonary disease? cigarette, cigar, or pipe smoking What triggers an asthma attack? cigarette smoke, mold, air pollution, pet hair or dander, cold air, exercise, dust, pollen, or emotional stress Check Your Understanding, page 320 1. nasopharyngitis 2. two to four 3. tonsillitis Chapter 9 Answer Key 2 Check Your Understanding, page 323 1. Acute bronchitis is characterized by a cough that may or may not produce mucus. Bronchitis is classified as chronic when a person has had a cough for anywhere from three months to two years. 2. Tuberculosis is contracted by breathing in air droplets from the cough or sneeze of an infected person. 3. cigarette, cigar, or pipe smoking 4. emphysema Check Your Understanding, page 325 1. 8% 2. limiting exposure to triggers and using prescription medications such as bronchodilators, antiinflammatory drugs, and inhaled steroids 3. smoking 4. Lung cancer is difficult to treat because it metastasizes (spreads) quickly throughout the body. 8. COPD is any lung disorder characterized by a longterm airway obstruction, making it difficult to breathe. Analyze and Apply 9. tuberculosis 10. Inspiration and expiration for a person with emphysema or chronic bronchitis will be limited, compared to a person with healthy pulmonary function, because lungs affected by emphysema or chronic bronchitis are unable to expand due to stiffness. 11. People with a family history of allergies are at a higher risk for asthma because many of the same stimuli that trigger allergies also cause asthma attacks. 12. Purse-lipped breathing is recommended for people with COPD because it helps maximize breathing and ease shortness of breath. Caption Questions In the Lab Figure 9.12: Wash your hands often with soap and hot (or warm) water, and avoid touching your eyes, nose, and mouth with your hands. 13. Pamphlet content will vary. Figure 9.14: In people with emphysema and chronic bronchitis, the concave-shaped expiration pattern is caused by the inability of stiff lungs to expand. Figure 9.15: COPD Taking It Further, page 324 1. Responses will vary. 2. To help manage her exercise-induced asthma, the team member could use an inhaler or bronchodilator about ten minutes before exercise or a game to control and prevent symptoms. As part of her overall asthma management routine, she should use an inhaled corticosteroid. In addition, warming up before exercise and cooling down afterward can help prevent an exercise-induced asthma attack. The athlete should also restrict exercise on days when the temperature is very low, the pollen count is high, or air pollution levels are high. Finally, infections can trigger an asthma attack, so the athlete should limit exercise when she has a cold or sinus infection. Know and Understand 1. group A streptococcus 2. laryngitis 3. By sneezing into your sleeve, you avoid contaminating your hands, which helps prevent the spread of infection. 4. Upper respiratory tract illnesses can be prevented by covering your nose and mouth when you cough or sneeze, washing your hands often using soap and hot (or warm) water, using an alcohol-based hand sanitizer, and not touching your nose, mouth, or eyes with your hands. 5. a fever over 100 degrees, fatigue, aching muscles, headache, nasal congestion, alternating chills and sweating, and a dry cough 6. acute bronchitis, pneumonia, tuberculosis 7. Pneumonia is treated with antibiotics and supplemental oxygen, as needed. Introduction to Anatomy and Physiology Chapter Assessments Lesson 9.1 Functions and Anatomy of the Respiratory System 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. carbon dioxide C cilia True Sinuses True voice box C True primary bronchi alveoli False The conchae increase the turbulence of the airflow in the nasal passage, allowing more particles to be trapped in the mucous membranes that line the nasal cavity and conchae. This filtering method is effective because it keeps fewer particles from entering the lungs. 14. Because there is no cartilage on the posterior side of the trachea, the C-rings are flexible, allowing the trachea to expand. This function is helpful when large food particles pass through the esophagus, which lies behind the trachea. Lesson 9.2 Respiration: Mechanics and Control 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. gas exchange respiration A Inspiration False C True B D A. Tidal volume is the amount of air inhaled during a normal breath, and inspiratory reserve volume is the Chapter 9 Answer Key 3 25. 26. 27. 28. amount of air that can be inhaled immediately after a normal inspiration. B. Expiratory volume is the amount of air that can be exhaled immediately after a normal expiration, and vital capacity is the amount of air that can be expired after a maximal inspiration. C. FEV1 is the maximum amount of air that a person can expire in one second, and ERV is the amount of air that can be exhaled immediately after a normal expiration. True C The formula is used to determine total lung capacity (TLC). IRV means inspiratory reserve volume, the amount of air that can be inhaled immediately following a normal inspiration; ERV means expiratory reserve volume, the amount of air that can be exhaled immediately following a normal expiration; RV means reserve volume, the volume of air that never leaves the lungs. These four elements equal total lung capacity because they comprise all the ways in which air exists in, and moves through, the lungs. It is not possible to hold your breath for long periods of time because of the neural and chemical factors that control breathing rate. When you hold your breath, your body’s need for oxygen is registered by the medulla and pons, which stimulate the intercostal muscles to move, causing you to inhale or exhale. In addition, during breath-holding, central chemoreceptors detect high levels of carbon dioxide in the body, and peripheral chemoreceptors detect low levels of oxygen. The chemoreceptors stimulate breathing by sending neural impulses to the inspiratory center via the vagus and glossopharyngeal nerves. Lesson 9.3 Respiratory Disorders and Diseases 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. A pharyngitis larynx (voice box) D False viral False chronic bronchitis C smoking C True True chemotherapy influenza; the patient has classic flu symptoms, and the sudden onset of these symptoms is indicative of the flu. 44. The term pink puffers is associated with emphysema because the exertion of breathing causes patients with this disease to develop a pink appearance. By contrast, the term blue bloaters is associated with chronic bronchitis because the lips and face of patients with this form of COPD often turn blue because of hypoxemia, and they develop a bloated appearance due to increased residual volume. Introduction to Anatomy and Physiology Building Skills and Connecting Concepts Analyzing and Evaluating Data 45. Toua’s symptoms indicate asthma because airway constriction, marked by chest tightness, wheezing, and breathlessness, is the main characteristic of asthma. This airway constriction is caused by bronchospams, contractions of the smooth bronchial muscles. 46. Tidal volume is the amount of air inhaled during a normal breath. Toua’s low tidal volume indicates that his airways are constricted, preventing him from drawing a complete breath. 47. Toua’s vital capacity—the total amount of air that he can forcibly exhale from his lungs after a maximum inhalation—indicates an asthmatic condition. A below-average VC suggests asthma because it indicates that the airways are constricted, preventing the lungs from completely filling with air. 48. It is possible for a person with asthma to have a TLC in the normal range. This is because, in the absence of an asthma attack, the person does not experience airway obstruction. Communicating about Anatomy and Physiology 49. Findings will vary. 50. Examples: The integumentary system not only helps the lymphatic system protect the body against foreign invaders, but it also protects all the other internal organ systems. The skeletal and muscular systems work together to move the body. The endocrine and reproductive systems work together to produce and regulate certain hormones, such as those involved in growth and development of the male and female reproductive systems. The digestive and urinary systems work together to extract nutrients from food and liquids and excrete waste products. Lab Investigations 51. Results will vary. 52. Results will vary. 53. Answers will vary. Workbook Lesson 9.1: Learning the Key Terms 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. A F O J M C N R B H I S Chapter 9 Answer Key 4 13. 14. 15. 16. 17. 18. 19. 20. Q E P K T D L G Lesson 9.1: Study Questions 1. cardiopulmonary system; the blood, pumped through the body by the cardiovascular system, transports oxygen and carbon dioxide throughout the body. Oxygen is delivered to the blood by the respiratory system, while it also expels carbon dioxide from the body. 2. The respiratory system is divided into two parts: the upper respiratory tract and the lower respiratory tract. The upper respiratory tract includes the nose, mouth, nasal cavity, pharynx, and larynx. The lower respiratory tract consists of the trachea, bronchi, bronchioles, and lungs. The lungs contain alveoli, air sacs in which the important gas-exchange function occurs. 3. Answers may vary. passageway for air moving into, or out of the lungs; filter and removed foreign particles from inspired air; humidify and control the temperature of inspired air; produce sound (voice); produce a sense of smell (olfactory sense); aid in immune defense; conduct air to the lower respiratory tract 4. many more particles would enter the nose since the cilia traps and prevents them from entering the nose 5. increasing the surface area available for filtering inspired air; filtering inspired air by trapping particles in its mucous membranes 6. It is believed to play a small role in speech, but it also helps prevent food from entering the nasal cavity. 7. Answers may vary. lighten the weight of the head; warm and moisten inspired air; amplify the tone of the voice 8. the pharynx 9. Infection causes the sinuses to become swollen and filled with fluid and germs. This prevents the voice from projecting in its normal tone. 10. The Eustachian tubes of the middle ear drain into the nasopharynx. Because of this connection, an inner ear infection can cause an upper respiratory infection, or vice versa. 11. the tonsils 12. routing air and food to the proper passageways and producing speech 13. the epiglottis 14. Cartilaginous rings, or C-shaped rings, provide support and prevent the airway from collapsing. 15. in the alveoli 16. Answers may vary. The large surface area of the lungs provide almost unlimited numbers of sites for gas exchange between the blood and alveolar sacs. Introduction to Anatomy and Physiology The membranes of the alveolar wall and capillary walls are very thin, allowing carbon dioxide and oxygen to pass through them quickly and easily. Gases diffuse from areas of high concentration to low concentration. 17. the mediastinum 18. The right lung has three lobes, but the left lung only has two. 19. a sac of two slippery, serous membranes; One membrane, the parietal pleura, lines the thoracic wall and diaphragm. The other, the visceral pleura, covers the lungs. Both pleura membranes secrete a serous (watery) fluid that allows the two linings to smoothly slide against each other as the lungs expand and contract during respiration. The serous fluid also acts like glue by keeping the two linings from pulling apart. Lesson 9.1: The Upper Respiratory Tract 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. J K F D M A R L P C H O E I B Q G N Lesson 9.1: The Anatomy of the Lungs 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. apex larynx clavicle left superior lobe mediastinum left inferior lobe base right inferior lobe middle lobe right superior lobe pleural sac Lesson 9.2: Learning the Key Terms 1. 2. 3. 4. Vital capacity (VC) respiratory gas transport External respiration inspiratory reserve volume (IRV) Chapter 9 Answer Key 5 5. forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 6. Peripheral chemoreceptors 7. pulmonary ventilation 8. central chemoreceptor 9. Internal respiration 10. forced expiratory volume in one second (FEV1) 11. total lung capacity (TLC) 12. Expiration 13. Mechanoreceptors 14. Respiration 15. functional residual capacity (FRC) 16. Hering-Breuer reflex 17. expiratory reserve volume (ERV) 18. Residual volume (RV) 19. Inspiration 20. Tidal volume (TV) Lesson 9.2: Study Questions 1. The main function of the respiratory system is gas exchange. 2. Pulmonary ventilation: air is continuously moved into and out of the lungs External respiration: fresh oxygen from outside (external to) the body fills the lungs and alveoli, allowing gas exchange between the alveoli and pulmonary blood Respiratory gas transport: the oxygen and carbon dioxide gases in the blood are transported between the lungs and different body tissues Internal respiration: gas exchange occurs inside the body between the tissues and capillaries 3. Boyle’s law states that the volume of a gas is inversely proportional to its pressure; or, as the volume of a gas increases, the pressure of the gas decreases. For the lungs to be able to take in air, the intrapulmonary pressure must be less than the atmospheric pressure. When the direction of airflow is reversed to expel air from the lungs, the intrapulmonary pressure must be greater than atmospheric pressure. 4. inhalation 5. the atmospheric pressure (760 mm Hg) is higher than the intrapulmonary pressure (757 mm Hg); this creates a vacuum, which sucks air into the lungs 6. Normal expiration is a passive process because it does not require muscle contraction. During exercise or when asthma or mucus accumulation narrows the respiratory passageways, expiration becomes an active process. In these instances, the internal intercostals muscles and abdominal muscles must contract to push air out of the lungs. 7. coughing, the need to clear dust or debris from the lower respiratory tract; sneezing, the need to clear the upper respiratory passages of dust or debris; hiccupping, sudden inspirations against the vocal cords of a close glottis; yawning, potentially caused by the need to increase oxygen in the lungs 8. 12 to 15 breaths per minute 9. because they have a smaller lung capacity than men 10. the medulla oblongata and the pons Introduction to Anatomy and Physiology 11. The Hering-Breuer reflex prevents overinflation of the alveolar sacs by alerting the medulla oblongata that the bronchioles and alveoli are full. 12. Central chemoreceptors monitor cerebrospinal fluid pH because this indicates the level of carbon dioxide in the body. Peripheral chemoreceptors are most sensitive to oxygen. 13. six liters 14. static and dynamic lung volume; Static lung volume measures only volume; dynamic lung volume measures volume based upon time. 15. static lung volume 16. Residual volume is important because it allows gas exchange to occur continuously between inspiration and expiration. 17. The pulmonary function test is a dynamic lung volume test. It can determine whether or not a person has asthma, obstructive lung disease, or restrictive lung disease. Lesson 9.3: Learning the Key Terms 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. E C H K F M G A J N D O I L B Lesson 9.3: Study Questions 1. upper respiratory tract illnesses (URIs) 2. by direct hand-to-hand contact, handling a contaminated object, and airborne droplets produced by unprotected sneezing or coughing 3. Answers may vary. cover nose and mouth with a tissue when coughing or sneezing; wash hands often; avoid touching your hands to your eyes, nose, or mouth 4. estimates are between 5% and 20% 5. sinusitis 6. Although similar in terms of sore throat, laryngitis is defined by loss of voice. 7. The former are lower respiratory tract illnesses, while the latter are upper respiratory tract illnesses. 8. the mucous membranes of the trachea and bronchial passageways; mostly characterized by a cough 9. the lungs 10. Chronic bronchitis is defined by a cough that persists for at least three months, while acute bronchitis is a temporary condition. 11. Answers may vary. smoking tobacco; exposure to secondhand smoke, pollution, or chemical fumes. Chapter 9 Answer Key 6 12. Emphysema causes chronic inflammation in the lungs, damaging the alveolar ducts and the alveolar sacs, and the pulmonary capillary bed. This damage decreases the surface area of the lungs, limiting the number of sites available for gas exchange. 13. Excessive mucus is produced in a patient with chronic bronchitis, limiting respiration and gas exchange. Also, bacteria can become trapped and breed in the warm, moist environment of the lungs. 14. wheezing, breathlessness, coughing (especially at night), and tightness in the chest 15. about 8% of adults and 9% of children 16. Lung cancer is the number one form of cancer leading to death in the US. 17. Answers may vary. Although exposure to secondhand smoke, radon, asbestos, and other toxins are risk factors, in 90% of lung cancer cases, smoking tobacco is the main cause. 18. Lung cancer metastasizes very quickly, so that usually by the time it is detected, it has progressed too far to treat. Lesson 9.3: Researching Respiratory Diseases and Disorders Answers may vary. Chapter 9: Respiratory System Statistics 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 300,000,000 1,500 80 0.75 12 to 15 757 763 40 25,000 2; 4 1; 5 8; 9 90 Chapter 9 Lab Investigation: Respiration 1. 2. 3. 4. 5. 6. 7. all answers will vary by individual all answers will vary by individual answers will vary by individual answers will vary by individual answers will vary by individual answers will vary by individual answers will vary by individual Conclusions 1. after exercise 2. Deeper breathing increases lung volume. 3. after exercise Introduction to Anatomy and Physiology 4. Shorter expiration/inspiration interval, faster breathing rate. 5. Breathing deep and breathing faster increase the amount of oxygen supplied to the blood. 6. after hyperventilating 7. As you hold your breath the carbon dioxide level in your blood increases. A high level of carbon dioxide causes you to take a breath. Hyperventilating decreases the amount of carbon dioxide in the blood, allowing you go longer without taking a breath. 8. Breathing rates are different if you are sitting or standing. You stood to collect consistent data. Chapter 9 Practice Test 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. thyroid cartilage pulmonary system Inspiration/Inhalation Boyle’s law Upper respiratory tract illnesses (URIs) T T F F T B D C A B H C F J A D I E G B J B A I H C D E F G Total lung capacity is a static lung volume measurement that is a combination of the vital capacity and the residual volume. It can be calculated using the following equation: IRV + TV + ERV + RV. 37. The epiglottis controls both the destination of food and liquid we consume and inhaled air. It is a small flap of cartilaginous tissue that covers the trachea when swallowing food and liquids to direct them down the esophagus. Chapter 9 Answer Key 7