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6 Cards in this Set

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The purest specimens of parietal cell secretion that have been obtained contain app....
0.17 N HCL with pHs as low as 0.87. The pH of the cytoplasm of the parietal cells, like that of other cells is 7-7,2.
What is it in the apical membrane of the parietal cells that pumps H+ against a concentration gradient of this magnitude.
It is the H+-K+ ATPase.
How are parietal cells anatomically positioned with respect to the gastric lumen?
The parietal cells are polarized, with an apical membrane facing the lumen of the gastric glands ans a basolateral membrane in contact with the interstitial fluid.
At rest, the cells contain abundant tubulovesicular structures with H+-K+ ATPase molecules in their walls. TRUE/FALSE
TRUE.
What happens when parietal cells are stimulated?
The tubulovesicular structures move to the apical membrane and fuse with it, thus inserting many more H+-K+ ATPase molecules into the membrane.
These ATPase molecules are now exposed to the K+ in the ECF and H+-K+ exchange begins.
What is the physiological process of HCL secretion?
1. H+ is secreted into the gastric lumen in exchange for K+ by H+-K+ ATPase.
2. HCO3- is exchanged for CL- in the interstitial fluid by an antiport, and Na+-K+ ATPase keeps intracellular Na+ low.