1. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 20 Control of Respiratory Function

2. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lung Functions Gas exchange –Moves O 2 into blood –Removes CO 2 from blood Blood storage Regulate vasoconstricting substances –Bradykinin –Angiotensin II –Heparin

3. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Conducting Airways Move air into lungs Warm and humidify air Trap inhaled particles

4. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory Airways Bronchioles Alveoli Gas is exchanged with the blood

5. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Membranes and Cavities Parietal pleura Visceral pleura Pleural space (between pleurae) Mediastinum

6. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which serous membrane lines the thoracic cavity? a.Visceral pleura b.Parietal pleura c.Visceral mediastinum d.Parietal mediastinum

7. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer b.Parietal pleura Rationale: The organs and walls of the thoracic and abdominal cavities are covered with serous membranes. Visceral membranes cover the organ; parietal membranes line the cavity walls. The two membranes and the space between them allow for ease of movement. The thoracic cavity is lined by parietal pleura; the lungs are covered by visceral pleura.

8. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory Muscles Diaphragm Accessory muscles of inhalation –External intercostals –Scalene –Sternocleidomastoid Accessory muscles of exhalation –Internal intercostals –Abdominal muscles

9. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. During inhalation, the diaphragm contracts and flattens.

10. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True Rationale: The diaphragm is the main muscle of inhalation/inspiration. During inhalation, the diaphragm contracts and flattens (it moves downward in order to accommodate the volume of air you are taking in, allowing space for the lungs to expand). During exhalation, the diaphragm relaxes and moves back up.

11. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Compliance How easily lungs can be inflated depends on: –Elastin and collagen fibers –Water content –Surface tension

12. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Surfactant Reduces Surface Tension

13. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Scenario A man’s lungs were damaged during a fire He developed severe respiratory distress The doctor said smoke inhalation had caused an inflammation of his alveoli The damage had also destroyed some of his surfactant Question: What had happened to his lung compliance? Why was he given positive-pressure ventilation?

14. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lung Volumes Tidal volume Inspiratory reserve Expiratory reserve Residual volume

15. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Lung Capacities Vital capacity Inspiratory capacity Functional residual capacity Total lung capacity

16. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Dynamic Lung Function Forced vital capacity Forced expiratory volume FEV 1.0 Minute volume Maximum voluntary ventilation

17. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which measure of lung function indicates the total amount of air that the lungs can hold? a.Tidal volume b.Functional residual capacity c.Vital capacity d.Total lung capacity

18. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer d.Total lung capacity Rationale: Total lung capacity is the maximum amount of air that the lungs can hold—everything (volume-wise) at the end of a maximal inhalation (the deepest breath one can possibly take). Normal TLC is approximately 6 L.

19. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Gas Exchange Oxygen moves from alveolar air into blood Carbon dioxide moves from blood into alveolar air

20. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Ventilation and Perfusion Scenario: A child has inhaled a peanut, blocking her left primary bronchus. Question: How will the ventilation in her two lungs change? How will the composition of the air in her two lungs differ? Which lung should she send more blood to? How should her body alter perfusion of the lungs?

21. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Ventilation–Perfusion Mismatching Blood goes to parts of the lung that do not have oxygen to give it Blood does not go to parts of the lung that have oxygen

22. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. Ventilation–perfusion mismatch results in hypoxia.

23. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True Rationale: In either case (ventilation without perfusion or perfusion without ventilation), oxygen is not picked up by the capillaries and delivered to the tissues. The result of decreased oxygen at the tissue level is termed hypoxia.

24. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Gases—Oxygen Dissolved oxygen = PaO 2 or PO 2 –Normal value >80 mm Hg Oxygen bound to hemoglobin = oxyhemoglobin –Normal value 95% to 97% saturation

25. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Hemoglobin Holds Four Oxygen Molecules O2O2 O2O2 O2O2 How saturated is this molecule of hemoglobin? How could a person have a hemoglobin saturation of 95%?

26. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxygen Capacity Amount of oxygen the blood can hold What is the oxygen capacity of normal blood? What is the oxygen capacity of anemic blood?

27. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxygen Release If the blood released half of its oxygen to the tissues: –How much oxygen would the normal tissues receive? –How much would the anemic person’s tissues receive?

28. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxygen Release (cont.) Most body tissues have a PO 2 of 40–60 mm Hg How much oxygen does the normal blood release at a PO 2 of 40 mm Hg? The anemic blood?

29. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Oxygen Affinity How tightly the hemoglobin holds onto the oxygen Which of these hemoglobin samples has the highest oxygen affinity? Which will release the most oxygen to the tissues? A B C

30. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Blood Gases—Carbon Dioxide Dissolved carbon dioxide = PaCO 2 or PCO 2 –Normal value 35–45 mm Hg Carbon dioxide bound to hemoglobin = carbaminohemoglobin Carbonic acid  bicarbonate ion and H + When you exhale you remove CO 2 from your blood and also decrease the amount of carbonic acid, raising your blood pH

31. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. The relationship between PCO 2 and pH is direct.

32. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: The relationship is indirect. As PCO 2 levels rise, the amount of carbonic acid in the blood increases, making the pH more acidic (decreasing it).

33. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins respiratory centers pneumotaxic apneustic stops inspiration; begins exhalation lungs deflate stretch receptors note decreased lung volume begins inspiration lungs inflate stretch receptors note increased lung volume

34. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chemoreceptors Can Adjust Respiration Rate Central chemoreceptors –Measure PCO 2 and pH in cerebrospinal fluid –Increase respiration when PCO 2 increases or pH decreases Peripheral chemoreceptors –Measure PO 2 in arterial blood –Increase respiration when PO 2 <60 mm Hg

35. Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Scenario You are caring for a COPD client He has chronically high PCO 2 He is being given low-flow oxygen and complains all the time that he “needs more air,” so you turn up his oxygen. Question: When you check on him later, he is unconscious and not breathing. What happened?