ANP 1107 Chapter Notes - Chapter 25-26: Metabolic Water, Cellular Respiration, Weak Base
3 Nov 2016
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Total plasma volume filters into the renal tubules about every 22 minutes. All our plasma would drain as urine in less than 30 minutes if it were not for tubular reabsorption. It reclaims most of the tubule contents and returns them to the blood. Selective transepithelial process beginning as soon as the filtrate goes into the proximal tubules. To reach the blood, reabsorbed substances follow either the trans-cellular or the para-cellular route. Trans-cellular: through apical membrane, cytosol, basolateral membrane of the tubule cell and then the endothelium of the peritubular capillaries. In the proximal nephron, the tight junctions are leaky and allow water and some ions (ca, na, mg, and k) to pass through para-cellular. Virtually all glucose and amino acids are completely reabsorbed to maintain normal plasma concentrations. Reabsorption of water and ions is constantly regulated in response to hormonal signals. Active requires atp directly (primary active) or indirectly (secondary active) Passive diffusion, facilitated diffusion, and osmosis (electrochemical gradient)
