Chapter 16 The Respiratory System: Pulmonary Ventilation PDF

500 CHAPTER 16 The Respiratory System: Pulmonary Ventilation Go to MasteringA&P for Interactive Physiology tutorials, Interactive Flowcharts, Dynamic Study Modules and more! CHAPTER REVIEW SUMMARY 16.1 Overview of Respiratory Function, p. 479 Respiration is the process of gas exchange; it includ...

500 CHAPTER 16 The Respiratory System: Pulmonary Ventilation Go to MasteringA&P for Interactive Physiology tutorials, Interactive Flowcharts, Dynamic Study Modules and more! CHAPTER REVIEW SUMMARY 16.1 Overview of Respiratory Function, p. 479 Respiration is the process of gas exchange; it includes both internal and external respiration. The four processes of external respiration are (1) pulmonary ventilation, (2) exchange of oxygen and carbon dioxide between lung air spaces and blood, (3) transport of oxygen and carbon dioxide in blood, and (4) exchange of oxygen and carbon dioxide between the blood and systemic tissues. Functions of the respiratory system include supply of oxygen to the tissues and elimination of carbon dioxide, management of the acid-base balance of the blood, vocalization, and protection against pathogens and irritants in the air. Copyright © 2017. Pearson Education, Limited. All rights reserved. 16.2 Anatomy of the Respiratory System, p. 479 The lungs are the major organs of the respiratory system; the right lung is divided into three lobes and the left lung is divided into two lobes. The upper airways include the nasal cavity, oral cavity, and pharynx. After the pharynx, a common passageway for air and food, the passageways for food and air diverge. The respiratory tract is the pathway for air. It can be functionally divided into two components: a conducting zone and a respiratory zone. The conducting zone—larynx, trachea, bronchi, and bronchioles—functions in conducting air from the larynx to the lungs. The conducting zone is lined by epithelium that contains goblet cells and ciliated cells. The respiratory zone—respiratory bronchioles, alveolar ducts, alveoli, and alveolar sacs—is the site of gas exchange within the lungs; the alveoli are the primary sites of exchange. The wall of an alveolus contains type I cells and type II cells. The type I cells and endothelial cells of capillaries form the respiratory membrane, across which gas exchange occurs. The type II cells secrete pulmonary surfactant. Alveolar macrophages are also located in the alveoli. The chest wall consists of the rib cage, the sternum, the thoracic vertebrae, and associated muscles and connective tissue. Muscles of the chest wall include the internal and external intercostals and the diaphragm. The pleurae are membranes that line the chest wall and lung, forming a pleural sac around each lung. The space between the two membranes, called the intrapleural space, is filled with a thin layer of intrapleural fluid. Respiratory, Anatomy Review: Respiratory Structures Respiratory, Control of Respiration 16.3 Forces for Pulmonary Ventilation, p. 487 The four primary pressures associated with ventilation are atmospheric pressure, intra-alveolar pressure, intrapleural pressure, and transpulmonary pressure. Atmospheric pressure is the pressure of the air outside the body. Intra-alveolar pressure is the pressure of air within the alveoli. Intrapleural pressure is the pressure of the intrapleural fluid. It is always negative during normal breathing, and always less than intra-alveolar pressure. Because the lungs and the chest wall are elastic, between breaths the chest wall tends to recoil outward, and the lungs to recoil inward. These forces tend to separate the chest wall from the lungs, thereby creating a negative intrapleural pressure. Transpulmonary pressure is the difference between the intrapleural pressure and the intra-alveolar pressure. Inspiration and expiration are driven by differences in atmospheric and intraalveolar pressures. These pressure gradients are created when the volume of the lungs is changed. Inspiration is caused by contraction of the diaphragm and the external intercostal muscles; when these muscles contract, the volume of the thoracic cavity increases. As the thoracic cavity expands, the intrapleural pressure decreases, creating a force that expands the lungs as the chest wall expands. When intra-alveolar pressure decreases below atmospheric pressure, inspiration occurs. During quiet breathing, expiration occurs when the chest wall and lungs return passively to their original positions. Active expiration involves contraction of the internal intercostals and abdominal muscles. Respiratory, Pulmonary Ventilation 16.4 Factors Affecting Pulmonary Ventilation, p. 491 The rate of air flow into or out of the lungs is determined by the magnitude of the pressure gradient driving the flow and airway resistance. Lungs have a high compliance; they are easily stretched to increase lung volume for inspiration. Airway resistance depends primarily on the radius of the tubules of the respiratory tract. Airway resistance generally is low but can be affected by breathing mechanics, the autonomic nervous system, chemical factors, and pathological states. Respiratory, Pulmonary Ventilation 16.5 Clinical Significance of Respiratory Volumes and Air Flows, p. 495 Spirometry measures lung volumes and capacities. Stanfield, Cindy. Principles of Human Physiology, Global Edition, Pearson Education, Limited, 2017. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/mqu/detail.action?docID=5187887. Created from mqu on 2023-08-21 23:35:41. CHAPTER 16 Lung volumes include tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. The various lung capacities include inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity. Other lung measurements take into account the rate of air flow. The forced vital capacity is the amount of air a person can expire following a The Respiratory System: Pulmonary Ventilation maximum inspiration, expiring as forcefully and rapidly as possible. The forced expiratory volume is a measure of the percentage of the forced vital capacity that can be exhaled within a certain time frame. Minute ventilation is the total amount of air that flows into or out of the respiratory system in a minute. Minute alveolar ventilation is a measure of the volume of fresh air reaching 501 the alveoli each minute, calculated as minute ventilation corrected for dead space volume. To increase minute alveolar ventilation, it is more efficient to increase tidal volume than to increase respiration rate. The maximum rate a person can exhale is called the peak expiratory flow rate (PEFR); PEFR varies by age and gender. EXERCISES Multiple-Choice Questions 1. Which of the following is a component of external respiration? a) Oxidative phosphorylation b) Pulmonary ventilation c) Production of carbon dioxide as a waste product d) Generation of ATP e) All of the above Copyright © 2017. Pearson Education, Limited. All rights reserved. 2. Which of the following is not a function of the conducting zone of the respiratory system? a) Humidifying the air b) Adjusting the air to body temperature c) Exchanging gases between the respiratory system and the blood d) Secreting mucus e) Protecting the lungs from inhaled particles 3. The smallest airways in the conducting zone are a) Terminal bronchioles. b) Respiratory bronchioles. c) Alveolar ducts. d) Alveolar sacs. e) Bronchi. 4. Surfactant is secreted by a) Goblet cells. b) Alveolar macrophages. c) Type I cells. d) Type II cells. e) Ciliated cells. 5. The product of tidal volume and breathing frequency gives a) Respiration rate. b) Total lung capacity. c) Alveolar ventilation. d) Minute ventilation. e) Dead space volume. 6. The maximum volume of air that can be expelled by the lungs following a maximum inspiration is the a) Expiratory reserve volume. b) Vital capacity. c) Tidal volume. d) Inspiratory reserve volume. e) Residual volume. 7. Which of the following statements describes the lungs at the functional residual capacity? a) Atmospheric, intra-alveolar, and intrapleural pressures are all equal. b) The lungs tend to collapse due to their elastic properties. c) The chest wall tends to collapse due to its elastic properties. d) Both a and c are true. e) All of the above are true. 8. Resistance to airflow is affected by a) Changes in transpulmonary pressure. b) Contractions of smooth muscles in the airways. c) Synthesis of mucus into the airways. d) All of the above. 9. For which of the following reasons is pulmonary surfactant synthesized by the alveoli? a) To decrease lung compliance b) To decrease its surface tension c) To facilitate lung expansion d) To increase airway resistance e) Both b and c 10. Which of the following muscles contract(s) during active expiration? a) Bronchial smooth muscle b) Internal intercostals c) External intercostals d) All of the above e) None of the above Objective Questions 11. Contraction of the diaphragm increases the rate of air flow during forced expiration. (true/false) 12. During inspiration, transpulmonary pressure (increases/decreases). 13. During inspiration, intrapleural pressure becomes (more/less) negative. 14. If airway resistance increases, a (higher/ lower) transpulmonary pressure is required to produce a given rate of air flow during expiration. 15. The respiratory membrane consists of type I cells and endothelial cells. (true/ false) 16. Pulmonary surfactant (increases/decreases) lung compliance. 17. The removes foreign particles from the airway. 18. (Obstructive/Restrictive) lung diseases cause a decrease in lung compliance. 19. cells secrete mucus. 20. The (internal/external) intercostals are muscles of inspiration. Essay Questions 21. Describe the various ways in which the structure of the respiratory system is adapted to facilitate gas exchange. 22. Describe the balance between distending pressures and recoil forces acting on the lungs and chest wall at FRC. Include an explanation of why intrapleural pressure is subatmospheric. 23. Explain the difference between minute ventilation and minute alveolar ventilation. Include a discussion of the effect of tidal volume on alveolar ventilation. Stanfield, Cindy. Principles of Human Physiology, Global Edition, Pearson Education, Limited, 2017. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/mqu/detail.action?docID=5187887. Created from mqu on 2023-08-21 23:35:41.