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Physiology Review

Physiology Review. Respiratory System. Introduction. This presentation does NOT cover lecture 25 External versus internal respiration RQ = CO 2 produced / O 2 consumed Thoracic cavity Pleurisy & pleural effusion Conducting versus respiratory zones Alveoli Mucociliary transport

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Physiology Review

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  1. Physiology Review Respiratory System Chris Mason, MS, MS-I

  2. Introduction • This presentation does NOT cover lecture 25 • External versus internal respiration • RQ = CO2 produced / O2 consumed • Thoracic cavity • Pleurisy & pleural effusion • Conducting versus respiratory zones • Alveoli • Mucociliary transport • Sol & gel layers • Ciliary dyskinesia • Silicosis • Other defects Chris Mason, MS, MS-I

  3. Lung Volumes & Capacities Chris Mason, MS, MS-I

  4. Lung Volumes & Capacities Chris Mason, MS, MS-I

  5. Lung Volumes & Capacities Chris Mason, MS, MS-I

  6. Lung Volumes & Capacities • Patient with tidal volume of 0.5 L is breathing at 15 breaths / minute • PCO2 arterial blood is 40 mm HG • PCO2 expired air is 36 mm Hg • What is alveolar ventilation rate Chris Mason, MS, MS-I

  7. Lung Volumes & Capacities Chris Mason, MS, MS-I

  8. Lung Volumes & Capacities • = (VT – dead space air) x breaths / minute • = (0.5 L – 0.05 L) x 15 breaths / minute • = 0.45 L x 15 breaths / minute • = 6.75 L / breath / minute Chris Mason, MS, MS-I

  9. Breathing Mechanics • Muscles of inspiration • Diaphragm • Most important • When diaphragm contracts • Stomach contents pushed down • Ribs lifted up & out • During exercise & respiratory distress • External intercostals • Accessory breathing muscles Chris Mason, MS, MS-I

  10. Breathing Mechanics • Muscles of expiration • Normally passive • Lung – chest wall system is elastic & normally returns to resting position after inspiration • During exercise & under conditions of ↑ airway resistance • Asthma • Abdominal muscles • Compress abdominal cavity • Push diaphragm up • Push air out of lungs • Internal intercostals • Pull ribs down & in Chris Mason, MS, MS-I

  11. Breathing Mechanics ↓ C → lungs least distensible ↑ C → lungs most distensible Chris Mason, MS, MS-I

  12. Breathing Mechanics Chris Mason, MS, MS-I

  13. Breathing Mechanics Chris Mason, MS, MS-I

  14. Breathing Mechanics Chris Mason, MS, MS-I

  15. Breathing Mechanics Chris Mason, MS, MS-I

  16. Breathing Mechanics • Relationships between pressure, airflow & resistance are analogous to those between blood pressure, blood flow & resistance in CV system Chris Mason, MS, MS-I

  17. Breathing Mechanics • Factors that change airway resistance • Major site of resistance is medium sized bronchi • Smallest airways are in parallel and therefore do NOT offer highest resistance Chris Mason, MS, MS-I

  18. Breathing Mechanics • Breathing cycle • At rest • During inspiration • During expiration Chris Mason, MS, MS-I

  19. Breathing Mechanics • Lung diseases • Asthma • COPD • Fibrosis Chris Mason, MS, MS-I

  20. Gas Exchange • Dalton’s law • Partial pressure = PTOTAL x fractional gas concentration • Partial pressures • Physiologic shunt • Dissolved gases • Henry’s law Chris Mason, MS, MS-I

  21. Gas Exchange • Diffusion of gases • Fick’s law • Perfusion-limited & diffusion limited gas exchange Chris Mason, MS, MS-I

  22. O2 Transport • O2 carried in blood either dissolved or bound to Hb • Hb, at its normal concentration, ↑ O2 carrying capacity of blood x 70 Chris Mason, MS, MS-I

  23. O2 Transport Chris Mason, MS, MS-I

  24. O2 Transport Chris Mason, MS, MS-I

  25. O2 Transport Chris Mason, MS, MS-I

  26. O2 Transport Chris Mason, MS, MS-I

  27. O2 Transport • Hypoxemia • Causes • ↑ altitude (↓ Patm) • ↓ PaO2 + normal A-a gradient • Hypoventilation (↓ PAO2) • ↓ PaO2 + normal A-a gradient • Diffusion defect (fibrosis) • ↓ PaO2 + ↑ A-a gradient • V / Q defect • ↓ PaO2 + ↑ A-a gradient • Right to left shunt • ↓ PaO2 + ↑ A-a gradient Chris Mason, MS, MS-I

  28. O2 Transport • Hypoxia • Causes • ↓ cardiac output via ↓ blood flow • Hypoxemia via ↓ PaO2 causing ↓ Hb % saturation • Anemia via ↓ [Hb] causing ↓ blood O2 content • CO poisoning via ↓ blood O2 content • Cyanide poisoning ↓ O2 utilization by tissues Chris Mason, MS, MS-I

  29. CO2 Transport Chris Mason, MS, MS-I

  30. Pulmonary Circulation • Pressures, resistance & cardiac output • Distribution of pulmonary blood flow • Supine versus standing • Zones 1, 2 & 3 of lungs Chris Mason, MS, MS-I

  31. Pulmonary Circulation • Regulation of pulmonary blood flow • Shunts Chris Mason, MS, MS-I

  32. Ventilation / Perfusion Defects Chris Mason, MS, MS-I

  33. Ventilation / Perfusion Defects Chris Mason, MS, MS-I

  34. Control of Breathing • Sensory information (PCO2, lung stretch, irritants, muscle spindles, tendons & joints) is coordinated in the brain stem • Medulla & pons • Brain stem output controls respiratory muscles & breathing cycle • Central control • Chemoreceptors • Other receptors Chris Mason, MS, MS-I

  35. Control of Breathing • Central control continued Chris Mason, MS, MS-I

  36. Control of Breathing • Chemoreceptors • Central • Peripheral Chris Mason, MS, MS-I

  37. Control of Breathing • Other receptors Chris Mason, MS, MS-I

  38. Integrated Responses • Exercise Chris Mason, MS, MS-I

  39. Integrated Responses • Adaptation to high altitude Chris Mason, MS, MS-I

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