Gas Exchange in Tissues

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Respiratory

Gas Exchange in Muscle/Tissue
- Oxygen is exchanged for carbon dioxide between body tissues and systemic capillaries
  - Gases diffuse down their concentration gradients
    - High concentration → low concentration
  - Muscle cells: Low pO2, high CO2
    - O2 diffuses from systemic capillaries to muscle cells
    - CO2 diffuses from muscle cells to systemic capillaries
- Optimization feature:
  - RBCs move through capillaries single-file
    - More RBC surface area is exposed, increasing efficiency of gas exchange
- Amount of gas dissolved in blood is determined by Henry’s Law (low yield)
  - C = P x solubility
    - C = concentration of dissolved gas
    - P = partial pressure of gas in equilibrium with the liquid
    - As partial pressure of a gas increases, concentration of gas dissolved in solution also increases
  - Application:
    - As O2 diffuses into capillaries from alveoli, pO2 of blood rises until it reaches the high pO2 in alveoli
    - This process facilitates dissolution of O2 in blood
    - Solubility of O2 in blood is not high enough for sufficient O2 to be dissolved for transport to body’s cells, so majority of O2 in blood is transported by Hb