Table 21.4 Comparison of Gas Partial Pressures and Approximate Percentages in the Atmosphere and in the Alveoli © 2014 Pearson Education, Inc.

© 2014 Pearson Education, Inc. Figure 21.17 Partial pressure gradients promoting gas movements in the body. Inspired air: PO2 PCO2 160 mm Hg 0.3 mm Hg Alveoli of lungs: PO2 PCO2 104 mm Hg 40 mm Hg External respiration Alveoli Pulmonary arteries Pulmonary veins (PO2 100 mm Hg) Blood leaving tissues and entering lungs: Blood leaving lungs and entering tissue capillaries: PO2 PCO2 40 mm Hg 45 mm Hg PO2 PCO2 100 mm Hg 40 mm Hg Heart Systemic veins Systemic arteries Internal respiration Tissues: PO2 less than 40 mm Hg PCO2 greater than 45 mm Hg © 2014 Pearson Education, Inc.

Figure 21.9a Alveoli and the respiratory membrane. Terminal bronchiole Respiratory bronchiole Smooth muscle Elastic fibers Alveolus Capillaries Diagrammatic view of capillary-alveoli relationships © 2014 Pearson Education, Inc.

Figure 21.9c Alveoli and the respiratory membrane. Red blood cell Nucleus of type I alveolar cell Alveolar pores Capillary Capillary Macrophage Alveolus Endothelial cell nucleus Alveolus Alveolar epithelium Respiratory membrane Fused basement membranes of alveolar epithelium and capillary endothelium Alveoli (gas-filled air spaces) Red blood cell in capillary Type II alveolar cell Type I alveolar cell Capillary endothelium Detailed anatomy of the respiratory membrane © 2014 Pearson Education, Inc.

PO2 104 mm Hg 150 100 PO2 (mm Hg) 50 40 0.25 0.50 0.75 Time in the Figure 21.18 Oxygenation of blood in the pulmonary capillaries at rest. 150 100 PO2 104 mm Hg PO2 (mm Hg) 50 40 0.25 0.50 0.75 Time in the pulmonary capillary (s) Start of capillary End of capillary © 2014 Pearson Education, Inc.

© 2014 Pearson Education, Inc. Figure 21.17 Partial pressure gradients promoting gas movements in the body. Inspired air: PO2 PCO2 160 mm Hg 0.3 mm Hg Alveoli of lungs: PO2 PCO2 104 mm Hg 40 mm Hg External respiration Alveoli Pulmonary arteries Pulmonary veins (PO2 100 mm Hg) Blood leaving tissues and entering lungs: Blood leaving lungs and entering tissue capillaries: PO2 PCO2 40 mm Hg 45 mm Hg PO2 PCO2 100 mm Hg 40 mm Hg Heart Systemic veins Systemic arteries Internal respiration Tissues: PO2 less than 40 mm Hg PCO2 greater than 45 mm Hg © 2014 Pearson Education, Inc.

What affects simple diffusion through respiratory membranes?

Consequences?

Solutions?

© 2014 Pearson Education, Inc. Figure 21.17 Partial pressure gradients promoting gas movements in the body. Inspired air: PO2 PCO2 160 mm Hg 0.3 mm Hg Alveoli of lungs: PO2 PCO2 104 mm Hg 40 mm Hg External respiration Alveoli Pulmonary arteries Pulmonary veins (PO2 100 mm Hg) Blood leaving tissues and entering lungs: Blood leaving lungs and entering tissue capillaries: PO2 PCO2 40 mm Hg 45 mm Hg PO2 PCO2 100 mm Hg 40 mm Hg Heart Systemic veins Systemic arteries Internal respiration Tissues: PO2 less than 40 mm Hg PCO2 greater than 45 mm Hg © 2014 Pearson Education, Inc.

Figure 21.22 Transport and exchange of CO2 and O2. Tissue cell Interstitial fluid (dissolved in plasma) Binds to plasma proteins Slow Chloride shift (in) via transport protein Fast Carbonic Anhydrase (Carbamino- hemoglobin) Red blood cell (dissolved in plasma) Blood plasma Oxygen release and carbon dioxide pickup at the tissues Alveolus Fused basement membranes (dissolved in plasma) Slow Chloride shift (out) via transport protein Fast Carbonic anhydrase (Carbamino- hemoglobin) Red blood cell (dissolved in plasma) Blood plasma © 2014 Pearson Education, Inc. Oxygen pickup and carbon dioxide release in the lungs

Figure 21.22a Transport and exchange of CO2 and O2. Tissue cell Interstitial fluid (dissolved in plasma) Binds to plasma proteins Slow Chloride shift (in) via transport protein Fast Carbonic anhydrase (Carbamino- hemoglobin) Red blood cell (dissolved in plasma) Blood plasma Oxygen release and carbon dioxide pickup at the tissues © 2014 Pearson Education, Inc.

Figure 21.22b Transport and exchange of CO2 and O2. Alveolus Fused basement membranes (dissolved in plasma) Slow Chloride shift (out) via transport protein Fast Carbonic anhydrase (Carbamino- hemoglobin) Red blood cell (dissolved in plasma) Blood plasma Oxygen pickup and carbon dioxide release in the lungs © 2014 Pearson Education, Inc.

Pontine respiratory centers interact with medullary Figure 21.23 Locations of respiratory centers and their postulated connections. Pons Medulla Pontine respiratory centers interact with medullary respiratory centers to smooth the respiratory pattern. Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration. Pons Medulla Dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG. To inspiratory muscles External intercostal muscles © 2014 Pearson Education, Inc. Diaphragm

(cerebral cortex—voluntary control over breathing) Figure 21.24 Neural and chemical influences on brain stem respiratory centers. Higher brain centers (cerebral cortex—voluntary control over breathing) + Other receptors (e.g., pain) and emotional stimuli acting through the hypothalamus – + – Respiratory centers (medulla and pons) Peripheral chemoreceptors + Stretch receptors in lungs + – Central chemoreceptors – Irritant receptors + Receptors in muscles and joints © 2014 Pearson Education, Inc.

Figure 21.27 The pathogenesis of COPD. • Tobacco smoke • Air pollution α-1 antitrypsin deficiency Continual bronchial irritation and inflammation Breakdown of elastin in connective tissue of lungs Chronic bronchitis Emphysema • Excess mucus production • Destruction of alveolar walls • Chronic productive cough • Loss of lung elasticity • Airway obstruction or air trapping • Dyspnea • Frequent infections • Hypoventilation • Hypoxemia • Respiratory acidosis © 2014 Pearson Education, Inc.