Active Transport and the Maintenance of Transmembrane Ionic Distributions
In all the discussion to this point I have not considered the question of how biological cells are able to maintain asymmetric transmembrane ion concentrations. In most cells there is a high external and a low internal concentration of Na+; the situation is reversed for K+. Taking Na+ as an example, it would be expected to diffuse into a cell because of the concentration gradient. Further, there should be an influx of Na+ because of the membrane electric field. From simple thermodynamic concepts this process should continue until external and internal Na+ concentrations are equal.
KeywordsActive Transport Coupling Ratio Squid Giant Axon Active Transport System Active Transport Mechanism
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