62. Capillary lumen Alveolus Macrophage Capillary Alveolus Red blood cell Diffusion of CO 2 Diffusion of O 2 Capillary endothelium Interstitial space Alveolar epithelium Type I (squamous epithelial) cell of alveolar wall Type II (surfactant- secreting) cell Fluid with surfactant Respiratory membrane Cell of capillary wall Alveolar fluid (with surfactant) Basement membrane of alveolar epithelium Basement membrane of capillary endothelium Respiratory membrane
65. Alveolus Diffusion of CO 2 Diffusion of O 2 Capillary Alveolar wall Blood flow (from body tissues) Blood flow (to body tissues) P CO 2 = 45 mm Hg P CO 2 = 40 mm Hg P O 2 = 40 mm Hg P O 2 = 104 mm Hg P O 2 = 104 mm Hg P CO 2 = 40 mm Hg
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71. Alveolus Capillary 2 2 2 (a) (b) Blood flow (from body tissues) Alveolar wall Oxygen molecules Hemoglobin molecules Diffusion of oxygen Oxyhemoglobin molecule Hemoglobin molecules Diffusion of oxygen Blood flow (to lungs) Blood P O = 40 mm Hg Blood P O = 95 mm Hg Tissue cells Tissue P O = 40 mm Hg
72. 10 20 30 40 50 60 70 80 90 100 Oxyhemoglobin dissociation at 38°C % saturation of hemoglobin 10 0 40 50 60 70 90 80 100 1 10 120 130 140 20 30 P O 2 (mm Hg)
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78. Tissue cell Cellular CO 2 Plasma Red blood cell Capillary wall Blood flow to systemic venule Tissue P CO 2 = 45 mm Hg CO 2 dissolved in plasma P CO 2 = 40 mm Hg Blood flow from systemic arteriole CO 2 combined with hemoglobin to form carbaminohemoglobin H 2 CO 3 H + combines with hemoglobin P CO 2 = 45 mm Hg HCO 3 - + H + CO 2 + H 2 O HCO 3 -
80. CO 2 CO 2 Alveolus Alveolar wall Capillary wall CO 2 HCO 3 - Carbaminohemoglobin Plasma Red blood cell P CO 2 = 45 mm Hg P CO 2 = 40 mm Hg CO 2 CO 2 dissolved in plasma Blood flow from pulmonary arteriole HCO 3 - + H + H 2 CO 3 H + released from hemoglobin Blood flow to pulmonary venule P CO 2 = 40 mm Hg + H 2 O CO 2 + hemoglobin