Electroneutrality, breakdown

This breakdown of electroneutrality in the solution, in the vicinity of the electrode, is a fundamental characteristic of the double-layer region. The next question is how far this double-layer region (interphase) extends out from the electrode into the solution. This question can be answered on the basis of analysis of the potential variation (distribution) in the double layer. 

All this is another way of saying that the center of the positive charge tends to separate from the center of the negative charge (Fig. 4.76). Hence, there is a tendency for the segregation of charge and the breakdown of the law of electroneutrality. 

The last mediator of gastric secretion in the parietal cell is an H+,K+-ATPase (proton or acid pump) which is a member of the phosphorylating class of ion transport ATPases. Hydrolysis of ATP results in ion transport. This chemical reaction induces a conformational change in the protein that allows an electroneutral exchange of cytoplasmic H+ for K+. The pump is activated when associated with a potassium chloride pathway in the canalicular membrane which allows potassium chloride efflux into the extracytoplasmic space, and thus results in secretion of hydrochloric acid at the expense of ATP breakdown. The activity of the pump is determined by the access of K+ on this surface on the pump. In the absence of K+, the cycle stops at the level of the phosphoenzyme [137]. 

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