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RESPIRATORY SYSTEM

RESPIRATORY SYSTEM. Marieb - Chapter 22. Respiratory Processes. Pulmonary Ventilation. External Respiration. Transport of Respiratory Gases. Internal Respiration. Conducting Zone. Respiratory Zone. Larynx. Cartilages of the Larynx. Trachea & Bronchi. Trachea.

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RESPIRATORY SYSTEM

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  1. RESPIRATORY SYSTEM Marieb - Chapter 22

  2. Respiratory Processes • Pulmonary Ventilation • External Respiration • Transport of Respiratory Gases • Internal Respiration

  3. Conducting Zone Respiratory Zone

  4. Larynx

  5. Cartilages of the Larynx

  6. Trachea & Bronchi

  7. Trachea

  8. Bronchi & Bronchioles

  9. Bronchioles and Alveoli Bronchiole if <1mm diameter

  10. Boyle’s Law P1V1 = P2V2 Robert Boyle (1627-1691)

  11. Physical Factors Influencing Pulmonary Ventilation • Airway Resistance - The major source is friction encountered in the respiratory passages. • Alveolar Surface Tension - force created by alveolar fluid that resists lung distension. Surfactant (surface active agent) lowers surface tension. • Lung Compliance - The distensibility (stretchiness) of lung tissue and the thoracic cage.

  12. ASTHMA • Bronchiole smooth muscle is sensitive to neural and chemical controls. • In an asthma attack, bronchioles first become inflamed, then the muscle constricts causing airways to narrow. • Risk factors include exposure to indoor allergens during infancy, allergies, and a family history of asthma.

  13. Respiratory Volumes M F

  14. Minute Ventilation = Tidal Volume X Respiratory Rate MV = TV x RR = 500 ml/breath X 12 breaths/min = 6000 ml/min

  15. Dead volume = 1ml/pound ideal body weight

  16. “Fresh” inspired air is diluted by the left over air remaining in the lungs from the previous breathing cycle.

  17. Alveolar Ventilation = (Tidal Volume - Dead Space) X Respiratory Rate AVR = (TV - ADS) x RR = (500 ml/breath - 150 ml) X 12 breaths/min = 350 ml/breath X 12 breaths/min = 4200 ml/min

  18. Gaseous Exchange Dalton’s Law of Partial Pressures Ptotal = P1 + P2 + . . . Pn John Dalton (1766-1844)

  19. Gaseous Exchange Henry’s Law A gas will dissolve in a liquid in proportion to its partial pressure William Henry (1775-1836)

  20. ATMOSPHERE ALVEOLI GAS % P P % N2 78.6 597 74.9 569 O2 20.9 159 13.7 104 CO2 0.04 0.3 5.2 40 0.46 3.7 6.2 47 H2O 100% 760 100% 760 1 atmosphere= 1 Torr = 760mmHg

  21. ATMOSPHERE ALVEOLI GAS % P P % N2 78.6 597 74.9 569 O2 20.9 159 13.7 104 CO2 0.04 0.3 5.2 40 0.46 3.7 6.2 47 H2O 100% 760 100% 760

  22. Gas Solubilities • CO2 is about 20X more soluble in plasma than O2 • N2 is practically insoluble.

  23. Respiratory Membrane 5 m thick in healthy lungs thickness gas diffusion Tuberculosis Pneumonia Total Surface Area 75 m2 in healthy lungs surface area gas diffusion Emphysema Lung Cancer

  24. OXYGEN TRANSPORT 1.5% dissolved in plasma 98.5% bound to hemoglobin Lungs HHb + O2 HbO2 + H+ tissues

  25. O2 Dissociation Curve PO2lung = 104mmHg

  26. PO2

  27. Bohr Effect

  28. CARBON DIOXIDE TRANSPORT 7-10% dissolved in plasma ~20% bound to hemoglobin CO2 + Hb HbCO2 ~70% as bicarbonate ion (HCO3-) carbonic anhydrase CO2 + H2O H2CO3 H+ + HCO3-

  29. CO2 Transport: Tissue CO2 diffuses into plasma and into the RBC RBCs contain carbonic anhydrase which rapidly combine H2O and CO2 to form H2CO3 H2CO3 quickly dissociates to H+ and HCO3- H+ ions become associated with protein portion of Hb (triggers the Bohr effect) HCO3- rapidly diffuses out of RBC into plasma Cl- moves into RBC to balance ionic charges (chloride shift) Figure 22.22a

  30. CO2 Transport: Lung In the lungs the process reverses HCO3- moves into the RBC Cl- shifts out of RBC HCO3- binds H+g H2CO3 Carbonic anhydrase splits H2CO3g H2O + CO2 CO2 moves down its partial pressure gradient to the alveoli Figure 22.22b

  31. THE END

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