Membrane Potential and Electrical Communication

In higher organisms, there is a noticeable imbalance in the equilibrium of ion distribution between the cell interior and the extracellular space (see Table 16.1). The concentration of Na and Cl ions is ca. 10-fold higher in the extracellular space than in the 

The membrane potential of a cell in the resting state is predominantly determined by two processes  

ATP-dependent Na7K ATPases transport Na ions outwards and K ions inwards against the concentration gradient. 

K leak chaimels permit entry of K ions along their concentration gradient from the interior to the exterior. 

The potential change depends on the nature of the ions crossing the membrane. If there is a Na influx, the membrane potential decreases and there is a depolarization. The membrane often gains a positive value by this process. In contrast, a efflux or a Cl influx leads to hyperpolarization. The membrane potential becomes more negative than the resting potential. 

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