Module 7: Figure HCl secretion
Control of HCl secretion by the parietal cell.
The fluid secretory mechanism (shown on the right) depends on the transfer of H+ and Cl− into the canaliculus through the operation of the H+/K+-ATPase and a Cl− channel respectively. These two ions then provide the osmotic gradient for a parallel flow of water. In resting cells, the H+/K+-ATPase is kept inactive by being withdrawn into the tubulovesicular system. During stimulation by a range of stimuli (see the text for details) the vesicles and tubules bearing the H+/K+-ATPase fuse with the apical membrane and secretion begins.