Gas Exchange: Lungs, Blood, Tissues

1. External Respiration (Air & Lungs)
   

1. Partial Pressure Gradients & Solubilities
• Oxygen: alveolar (104 mm) -------> blood (40 mm)
• Carbon Dioxide: blood (45 mm) -------> alveolar (40 mm) (carbon dioxide much more soluble than oxygen)
2. Alveolar Membrane Thickness (0.5-1.0 micron)
• very easy for gas to diffuse across alveoli
• edema - increases thickness, decreases diffusion
3. Total Alveolar Surface Area for Exchange
• total surface area healthy lung = 145 sq meters
• emphysema - decreases total alveolar surface area
4. Ventilation-Blood Flow Coupling
• low Oxygen in alveolus -> vasoconstriction
• high Oxygen in alveolus -> vasodilation
• high Carb Diox in alveolus -> dilate bronchioles
• low Carb Diox in alveolus -> constrict bronchioles

1. Oxygen: blood (104 mm) -------> tissues (40 mm)
2. Carbon Dioxide: tissues (>45 mm) -------> blood (40 mm)

Category: Physiology Notes