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About this Chapter

About this Chapter. Diffusion and solubility of gases Gas exchange in lungs and tissues Gas transport in the blood Regulation of ventilation. Overview. O 2. CO 2. Airways. Alveoli of lungs. O 2. CO 2. 6. CO 2 exchange at alveolar-capillary interface. Oxygen exchange

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About this Chapter

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  1. About this Chapter • Diffusion and solubility of gases • Gas exchange in lungs and tissues • Gas transport in the blood • Regulation of ventilation

  2. Overview O2 CO2 Airways Alveoli of lungs O2 CO2 6 CO2 exchange at alveolar-capillary interface Oxygen exchange at alveolar-capillary interface 1 O2 CO2 Pulmonary circulation Oxygen transport 2 5 CO2 transport Systemic circulation CO2 O2 4 CO2 exchange at cells Oxygen exchange at cells 3 CO2 O2 Cellular respiration Cells Nutrients ATP Overview of oxygen and carbon dioxide exchange and transport Figure 18-1

  3. Diffusion and Solubility Diffusion Rate : Surface area x Concentration Gradient x Membrane Permeability Membrane Thickness • Surface area • Constant • Concentration gradient • Most important factor • Membrane thickness • Constant • Diffusion distance • Constant • Thus, Diffusion Rate is proportional to Concentration Gradient

  4. Movement of Gases • Pressure gradient • Solubility of gas in liquid • Temperature (in body, relatively constant)

  5. Behavior of Gases in Solution (a) Initial state: no O2 in solution (b) Oxygen dissolves. (c) At equilibrium, PO2 in air and water is equal. Low O2 solubility means concentrations are not equal. PO2 = 100 mm Hg PO2 = 100 mm Hg [O2] = 5.20 mmol/L PO2 = 100 mm Hg PO2 = 0 mm Hg [O2] = 0.15 mmol/L Figure 18-2a–c

  6. Behavior of Gases in Solution (a) Initial state: no O2 in solution PO2 = 100 mm Hg PO2 = 0 mm Hg Figure 18-2a–c (1 of 3)

  7. Behavior of Gases in Solution (a) Initial state: no O2 in solution (b) Oxygen dissolves. PO2 = 100 mm Hg PO2 = 0 mm Hg Figure 18-2a–c (2 of 3)

  8. Behavior of Gases in Solution (a) Initial state: no O2 in solution (b) Oxygen dissolves. (c) At equilibrium, PO2 in air and water is equal. Low O2 solubility means concentrations are not equal. PO2 = 100 mm Hg PO2 = 100 mm Hg [O2] = 5.20 mmol/L PO2 = 100 mm Hg PO2 = 0 mm Hg [O2] = 0.15 mmol/L Figure 18-2a–c (3 of 3)

  9. Behavior of Gases in Solution Figure 18-2c–d

  10. Gas Exchange at the Alveoli and Cells PLAY Animation: Respiratory System: Gas Exchange Figure 18-3

  11. Partial Pressures

  12. Gas Exchange

  13. Causes of Low Alveolar PO2 • Inspired air has abnormally low oxygen content • Altitude • Alveolar ventilation is inadequate • Decreased lung compliance • Increased airway resistance • Overdose of drugs

  14. Alveolar Ventilation Pathological conditions that reduce alveolar ventilation and gas exchange Figure 18-4a

  15. Alveolar Ventilation Figure 18-4b

  16. Alveolar Ventilation Figure 18-4c

  17. Alveolar Ventilation Figure 18-4d

  18. Alveolar Ventilation Figure 18-4e

  19. Gas Exchange Oxygen diffuses across alveolar epithelial cells and capillary endothelial cells to enter the plasma Figure 18-5

  20. Gas Exchange • Pathological changes • Decrease in amount of alveolar surface area • Increase in thickness of alveolar membrane • Increase in diffusion distance between alveoli and blood

  21. Oxygen Transport ARTERIAL BLOOD Capillary endothelium O2 dissolved in plasma (~ PO2) < 2% O2 O2 + Hb Hb•O2 > 98% Red blood cell Alveolus Alveolar membrane Transport to cells Cells Hb + O2 Hb•O2 O2 Used in cellular respiration O2 dissolved in plasma Summary of oxygen transport in the blood Figure 18-6

  22. Oxygen Transport The role of hemoglobin in oxygen transport Figure 18-7a

  23. Oxygen Transport Figure 18-7b

  24. Oxygen Transport Figure 18-7c

  25. The Hemoglobin Molecule The amount of oxygen bound to hemoglobin depends on the PO2 of plasma Figure 18-8

  26. Oxygen-Hemoglobin Dissociation Curve Figure 18-9

  27. Oxygen Binding Physical factors alter hemoglobin’s affinity for oxygen Figure 18-10a

  28. Oxygen Binding Figure 18-10b

  29. Oxygen Binding Figure 18-10c

  30. 2,3-diphosphoglycerate (intermediate in glycolysis pathway) lowers Hb binding affinity 2,3-DPG alters hemoglobin’s affinity for oxygen Figure 18-11

  31. Oxygen Binding Differences in oxygen-binding properties of maternal and fetal hemoglobin Figure 18-12

  32. Oxygen Binding Factors contributing to the total oxygen content of arterial blood Figure 18-13

  33. Carbon Dioxide Transport • Dissolved: 7% • Converted to bicarbonate ion in rbc: 70% • Bound to hemoglobin: 23% • Hemoglobin also binds H+, • Hb and CO2: carbaminohemoglobin

  34. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Cl– Alveoli CA H2O + CO2 HCO3– H2CO3 HCO3– in plasma Hb•H H+ + Hb Figure 18-14

  35. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Cellular respiration in peripheral tissues Capillary endothelium Cell membrane Alveoli Figure 18-14 (1 of 17)

  36. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Capillary endothelium Cell membrane Alveoli Figure 18-14 (2 of 17)

  37. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 Capillary endothelium Cell membrane Alveoli Figure 18-14 (3 of 17)

  38. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Capillary endothelium Cell membrane Alveoli Figure 18-14 (4 of 17)

  39. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) CA CO2 + H2O H2CO3 Capillary endothelium Cell membrane Alveoli Figure 18-14 (5 of 17)

  40. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) HCO3– CA CO2 + H2O H2CO3 H+ + Hb Capillary endothelium Cell membrane Alveoli Figure 18-14 (6 of 17)

  41. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) HCO3– CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Alveoli Figure 18-14 (7 of 17)

  42. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Alveoli Figure 18-14 (8 of 17)

  43. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Alveoli Figure 18-14 (9 of 17)

  44. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Alveoli Figure 18-14 (10 of 17)

  45. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Alveoli Figure 18-14 (11 of 17)

  46. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Alveoli Figure 18-14 (12 of 17)

  47. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Cl– Alveoli HCO3– HCO3– in plasma Figure 18-14 (13 of 17)

  48. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Cl– Alveoli HCO3– HCO3– in plasma Hb•H H+ + Hb Figure 18-14 (14 of 17)

  49. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Cl– Alveoli HCO3– H2CO3 HCO3– in plasma Hb•H H+ + Hb Figure 18-14 (15 of 17)

  50. Carbon Dioxide Transport in the Blood VENOUS BLOOD CO2 Dissolved CO2 (7%) Cellular respiration in peripheral tissues Red blood cell CO2 + Hb Hb•CO2 (23%) Cl– HCO3– HCO3– in plasma (70%) CA CO2 + H2O H2CO3 H+ + Hb Hb•H Capillary endothelium Cell membrane Transport to lungs Dissolved CO2 Dissolved CO2 CO2 Hb + CO2 Hb•CO2 Cl– Alveoli CA H2O + CO2 HCO3– H2CO3 HCO3– in plasma Hb•H H+ + Hb Figure 18-14 (16 of 17)

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