Conditions for Countergradient Diffusion of Oxygen through a Hemoglobin Barrier
Diffusion against a concentration gradient is often observed in biological systems. In most cases such countergradient diffusion is accompanied by an energy producing metabolic process. This is termed an active transport process. Countergradient diffusion can also take place in a passive transport process, the energy is then supplied by another species diffusing in the direction of its gradient. Such countergradient diffusion can take place in the oxygen-carbon monoxide-hemoglobin system. Carboxyhemoglobin diffuses in the direction of the carbon monoxide gradient. To maintain a material balance hemoglobin must then diffuse back and can carry small amounts of oxygen against a concentration gradient of oxygen. The conditions for such countergradient diffusion are described by solutions of the coupled differential equations of diffusion.
KeywordsDiffusion Path Oxygen Flux Couple Differential Equation Carrier Molecule Hemoglobin Solution
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