Mechanics of Breathing

1. Mechanics of Breathing 17

2. About this Chapter • The respiratory system • Gas laws • Ventilation

3. Respiratory System • Exchange of gases between the atmosphere and the blood • Homeostatic regulation of body pH • Protection from inhaled pathogens and irritating substances • Vocalization

4. Principles of Bulk Flow • Flow from regions of higher to lower pressure • Muscular pump creates pressure gradients • Resistance to flow • Diameter of tubes

5. Respiratory System Overview of external and cellular respiration Figure 17-1

6. Respiratory System • Conducting system • Alveoli • Bones and muscle of thorax

7. Respiratory System Figure 17-2a

8. Muscles Used for Ventilation Figure 17-2b

9. The Respiratory System The relationship between the pleural sac and the lung Figure 17-3

10. Branching of Airways Figure 17-2e

11. Branching of the Airways Figure 17-4

12. Alveolar Structure Figure 17-2g

13. Pulmonary Circulation • Right ventricle  pulmonary trunk  lungs  pulmonary veins  left atrium PLAY Animation: Respiratory System: Anatomy Review

14. Gas Laws

15. Gas Laws Pgas = Patm % of gas in atmosphere

16. Boyle’s Law Gases move from areas of high pressure to areas of low pressure Figure 17-5

17. Spirometer Figure 17-6

18. Lungs Volumes and Capacities Figure 17-7

19. Conditioning • Warming air to body temperature • Adding water vapor • Filtering out foreign material

20. Ciliated Respiratory Epithelium Figure 17-8

21. Air Flow • Flow  P/R • Alveolar pressure or intrapleural pressure can be measured • Single respiratory cycle consists of inspiration followed by expiration

22. Movement of the Diaphragm Figure 17-9a

23. Movement of the Diaphragm Figure 17-9b

24. Movement of the Diaphragm Figure 17-9c

25. Movement of the Rib Cage during Inspiration Figure 17-10a

26. Movement of the Rib Cage during Inspiration Figure 17-10b

27. Pressure Changes during Quiet Breathing Figure 17-11

28. Pressure in the Pleural Cavity Figure 17-12a

29. Pressure in the Pleural Cavity Pneumothorax results in collapsed lung that can not function normally Figure 17-12b

30. Compliance and Elastance • Compliance: ability to stretch • High compliance • Stretches easily • Low compliance • Requires more force • Restrictive lung diseases • Fibrotic lung diseases and inadequate surfactant production • Elastance: returning to its resting volume when stretching force is released

31. Law of LaPlace Surface tension is created by the thin fluid layer between alveolar cells and the air Figure 17-13

32. Surfactant • More concentrated in smaller alveoli • Mixture containing proteins and phospholipids • Newborn respiratory distress syndrome • Premature babies • Inadequate surfactant concentrations

33. Air Flow PLAY Animation: Respiratory System: Pulmonary Ventilation

34. Ventilation Dead space filled with fresh air The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 150 mL 1 2700 mL 1 End of inspiration Atmospheric air 150 350 500 mL 2 Exhale 500 mL (tidal volume). Dead space is filled with fresh air. 2 150 mL 150 At the end of expiration, the dead space is filled with “stale” air from alveoli. 3 Respiratory cycle in an adult Only 350 mL of fresh air reaches alveoli. 350 2200 mL 150 2200 mL Dead space filled with stale air 4 The first 150 mL of air into the alveoli is stale air from the dead space. Inhale 500 mL of fresh air (tidal volume). 4 150 mL KEY 2200 mL 3 PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Total pulmonary ventilation and alveolar ventilation Total pulmonary ventilation = ventilation rate  tidal volume Figure 17-14

35. Ventilation Dead space filled with fresh air 150 mL 1 2700 mL 1 End of inspiration Respiratory cycle in an adult KEY PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Figure 17-14, step 1

36. Ventilation Dead space filled with fresh air The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 150 mL 1 2700 mL 1 End of inspiration 150 350 2 Exhale 500 mL (tidal volume). 2 150 mL Respiratory cycle in an adult 2200 mL KEY PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Figure 17-14, steps 1–2

37. Ventilation Dead space filled with fresh air The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 150 mL 1 2700 mL 1 End of inspiration 150 350 2 Exhale 500 mL (tidal volume). 2 150 mL At the end of expiration, the dead space is filled with “stale” air from alveoli. 3 Respiratory cycle in an adult 2200 mL Dead space filled with stale air 150 mL KEY 2200 mL 3 PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Figure 17-14, steps 1–3

38. Ventilation Dead space filled with fresh air The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 150 mL 1 2700 mL 1 End of inspiration Atmospheric air 150 350 500 mL 2 Exhale 500 mL (tidal volume). Dead space is filled with fresh air. 2 150 mL 150 At the end of expiration, the dead space is filled with “stale” air from alveoli. 3 Respiratory cycle in an adult Only 350 mL of fresh air reaches alveoli. 350 2200 mL 150 2200 mL Dead space filled with stale air 4 The first 150 mL of air into the alveoli is stale air from the dead space. Inhale 500 mL of fresh air (tidal volume). 4 150 mL KEY 2200 mL 3 PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Figure 17-14, steps 1–4

39. Ventilation Dead space filled with fresh air The first exhaled air comes out of the dead space. Only 350 mL leaves the alveoli. 150 mL 1 2700 mL 1 End of inspiration Atmospheric air 150 350 500 mL 2 Exhale 500 mL (tidal volume). Dead space is filled with fresh air. 2 150 mL 150 At the end of expiration, the dead space is filled with “stale” air from alveoli. 3 Respiratory cycle in an adult Only 350 mL of fresh air reaches alveoli. 350 2200 mL 150 2200 mL Dead space filled with stale air 4 The first 150 mL of air into the alveoli is stale air from the dead space. Inhale 500 mL of fresh air (tidal volume). 4 150 mL KEY 2200 mL 3 PO2 = 160 mm Hg PO2 ~ 100 mm Hg ~ Figure 17-14, steps 1–5

40. Ventilation Alveolar ventilation = ventilation rate  (tidal volume – dead space volume)

41. Ventilation

42. Ventilation

43. Ventilation Effects of changing alveolar ventilation on PO2 and PCO2 in the alveoli Figure 17-15

44. Ventilation

45. Ventilation Local control matches ventilation and perfusion Figure 17-16a

46. Ventilation Figure 17-16b

47. Ventilation Figure 17-16c

48. Ventilation • Auscultation = diagnostic technique • Obstructive lung diseases • Asthma • Emphysema • Chronic bronchitis

49. Summary • Respiratory system • Cellular respiration, external respiration, respiratory system, upper respiratory tract, pharynx, and larynx • Lower respiratory tract, trachea, bronchi, bronchioles, alveoli, Type I and Type II alveolar cells • Diaphragm, intercostal muscles, lung, pleural sac, and plural fluid • Gas Laws: Dalton’s law and Boyle’s law

50. Summary • Ventilation • Tidal volume, vital capacity, residual volume, and respiratory cycle • Alveolar pressure, active expiration, intrapleural pressures, compliance, elastance, surfactant, bronchoconstriction, and bronchodilation • Total pulmonary ventilation, alveolar ventilation, hyperventilation, and hypoventilation