Definition
- Gas exchange is diffusion of O2 and CO2 between alveolar air and capillary blood across the respiratory membrane, driven by partial pressure gradients.
- The respiratory membrane is normally 0.2 to 0.5 μ thick.
Factors Contributing to Gas Exchange
Factors determining gas uptake from the alveoli
Factor
Diffusion properties of the alveolar-capillary membrane
- Role
- Membrane structure and composition
Partial pressure gradient for the gas
- Role
- Driving force for diffusion
Pulmonary capillary blood flow
- Role
- Delivers and removes gas to sustain the gradient
Diffusing capacity of the gas through the membrane
- Role
- Overall rate of gas transfer