Diffusion of Gases across Alveolar-Capillary Membranes | ||
The rate of diffusion of a gas across a membrane depends on following factors | ||
1 |
The pressure difference across the membrane of the gas in the mixture - the higher the pressure difference the higher is rate of diffusion of the gas. | |
2 |
The surface area of available for gas diffusion - the larger the area, the higher is the rate of diffusion. | |
3 |
The solubility of the gas in water - the higher the solubility, the faster is the rate of diffusion. | |
4 |
The thickness of the membrane - the larger the thickness, the slower is the rate of diffusion. | |
5 |
The size of the gas molecule - the larger the size, the slower is the rate of diffusion |
In mathematical terms this can be written as :
V_{gas} = (P_{1} - P_{2}) x A x D/T where:
V_{gas} | _{=} |
Rate of gas diffusion |
(P_{1} - P_{2}) | = |
Pressure difference across the membrane |
A | = |
Surface Area of the membrane |
D | = |
Solubility of the gas/square root of the molecular weight |
T | = |
Thickness of the membrane |