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  • 1. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 1 Structure and Function of the Pulmonary System
  • 2. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 2 Structures of the Pulmonary System  Airways  Pulmonary circulation  Chest wall  Lungs  Lobes (three on right, two on left)  Segments  Lobules  Mediastinum
  • 3. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 3 Structures of the Pulmonary System (cont’d)
  • 4. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 4 Structures of the Pulmonary System (cont’d)  Conducting airways:  Upper airways: • Nasopharynx • Oropharynx  Larynx • Connects upper and lower airways  Lower airways: • Trachea • Bronchi • Terminal bronchioles
  • 5. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 5 Structures of the Pulmonary System (cont’d)
  • 6. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 6 Structures of the Pulmonary System (cont’d)  Gas-exchange airways:  Respiratory bronchioles  Alveolar ducts  Alveoli • Epithelial cells:  Type I alveolar cells – Alveolar structure  Type II alveolar cells – Surfactant production
  • 7. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 7 Structures of the Pulmonary System (cont’d)
  • 8. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 8 Structures of the Pulmonary System (cont’d)
  • 9. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 9 Pulmonary and Bronchial Circulation  Pulmonary circulation has a lower pressure than the systemic circulation  One-third of pulmonary vessels are filled with blood at any given time  Pulmonary artery divides and enters the lung at the hilus  Each bronchus and bronchiole has an accompanying artery or arteriole
  • 10. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 10 Pulmonary and Bronchial Circulation (cont’d)  Alveolocapillary membrane  Formed by the shared alveolar and capillary walls  Gas exchange occurs across this membrane  Pulmonary veins  Each drains several pulmonary capillaries  Dispersed randomly throughout the lung  Leave the lung at the hila and enter the left atrium
  • 11. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 11 Pulmonary and Bronchial Circulation (cont’d)
  • 12. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 12 Chest Wall and Pleura  Chest wall  Skin, ribs, and intercostal muscles  Thoracic cavity  Pleura  Serous membrane  Parietal and visceral layers  Pleural space (cavity)  Pleural fluid
  • 13. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 13 Thoracic Cavity
  • 14. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 14 Function of the Pulmonary System  Ventilate the alveoli  Diffuse gases into and out of the blood  Perfuse the lungs so the body receives oxygen
  • 15. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 15 Function of the Pulmonary System (cont’d)  Ventilation  Mechanical movement of gas or air into and out of the lungs  Minute volume • Ventilatory rate multiplied by the volume of air per breath  Alveolar ventilation
  • 16. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 16 Ventilation  Respiratory center • Dorsal respiratory group • Ventral respiratory group • Pneumotaxic center • Apneustic center  Peripheral chemoreceptors  Lung receptors: • Irritant receptors • Stretch receptors • J receptors  Chemoreceptors: • Central chemoreceptors • Peripheral chemoreceptors  Neurochemical control
  • 17. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 17 Neurochemical Respiratory Control
  • 18. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 18 Mechanics of Breathing  Major and accessory muscles:  Major muscles of inspiration: • Diaphragm • External intercostals  Accessory muscles of inspiration: • Sternocleidomastoid muscle • Scalene muscles  Accessory muscles of expiration: • Abdominal intercostal muscles • Internal intercostal muscles
  • 19. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 19 Muscles of Ventilation
  • 20. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 20 Mechanics of Breathing  Alveolar surface tension and ventilation  Function of surfactant  Elastic properties of the lung and chest wall:  Elastic recoil  Compliance  Airway resistance  Work of breathing
  • 21. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 21 Mechanics of Breathing (cont’d)
  • 22. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 22 Gas Transport  Four steps  Ventilation of the lungs  Diffusion of oxygen from the alveoli into the capillary blood  Perfusion of systemic capillaries with oxygenated blood  Diffusion of oxygen from systemic capillaries into the cells  Diffusion of CO2 occurs in reverse order
  • 23. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 23 Measurement of Gas Pressure  Barometric pressure  Partial pressure  Partial pressure of water vapor
  • 24. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 24 Measurement of Gas Pressure (cont’d)
  • 25. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 25 Gas Transport  Distribution of ventilation and perfusion  Gravity and alveolar pressure  Ventilation-perfusion ratio
  • 26. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 26 Gas Transport (cont’d)  Oxygen transport  Diffusion across the alveolocapillary membrane  Determinants of arterial oxygenation: • Hemoglobin binding • Oxygen saturation  Oxyhemoglobin association and dissociation • Oxyhemoglobin dissociation curve • Bohr effect
  • 27. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 27 Measurement of Gas Pressure
  • 28. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 28 Gas Transport  Carbon dioxide transport  Dissolved in plasma  Bicarbonate  Carbamino compounds  Haldane effect
  • 29. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 29 Control of Pulmonary Circulation  Hypoxic pulmonary vasoconstriction  Caused by low alveolar paO2  Blood is shunted to other, well-ventilated portions of the lungs • Provides better ventilation and perfusion matching • If hypoxia affects all segments of the lungs, the vasoconstriction can result in pulmonary hypertension
  • 30. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 30 Control of Pulmonary Circulation (cont’d)  Acidemia also causes pulmonary artery constriction
  • 31. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 31 Tests of Pulmonary Function  Spirometry  Diffusion capacity  Residual volume  Functional reserve capacity (FRC)  Total lung capacity  Arterial blood gas analysis  Chest radiographs
  • 32. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 32 Aging and the Pulmonary System  Loss of elastic recoil  Stiffening of the chest wall  Alterations in gas exchange  Increases in flow resistance  Decreased exercise tolerance
  • 33. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 33 Aging and the Pulmonary System (cont’d)