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5 Cards in this Set
- Front
- Back
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What does carbonic anhydrase do/
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It catalyzes the formation of H2CO3 and drugs that inhibit CA depress both secretion of acid by the proximal tubules and the reactions which depend on it.
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What is the difference between H+ secretion in the PCT and DCT?
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In the DCT and collecting ducts, H+ secretion is relatively independent of sodium in the tubular lumen. In this part of the tubule, most H+ is secreted by an ATP driven proton pump.
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How does aldosterone act on the proton pump?
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It acts on it to increase distal H+ secretion. The I cells in this part of the renal tubule secrete acid and like the parietal cells in the stomach, contain abundant carbonic anhydrase and numerous tubulovesicular structures.
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What is Band 3?
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The I cells contain Babd 3, an anion exchange protein, in their basolateral cell membranes and this protein may function as a Cl-HCO3 exchanger for the transport of HCO3 to the interstitial fluid.
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What is limiting pH?
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The maximal H+ gradient against which the transport mechanisms can secrete in humans corresponds to a urine pH of about 4.5, ie, an H+ concentration in the urine that is 1,000 times the concentration in plasma(pH 4.5 is thus the limiting pH).
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