Regulation of Urine Concentration

Regulation of Urine Concentration - Regulation of Urine...

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Regulation of Urine Concentration The nephron loop of juxtamedullary nephrons is the apparatus that allows the nephron to  concentrate urine. The loop is a countercurrent multiplier system in which fluids move in opposite  directions through side-by-side, semi-permeable tubes. Substances are transported horizontally, by  passive or active mechanisms, from one tube to the other. The movement of the transported  substances up and down the tubes results in a higher concentration of substances at the bottom of  the tubes than at the top of the tubes. Details of the process follow and are also shown in Figure 1:  The descending limb of the nephron loop is permeable to H 2 O, so H 2 O diffuses out into the  surrounding fluids. Because the loop is impermeable to Na +  and Cl  and because these ions  are not pumped out by active transport, Na +  and Cl  remain inside the loop. 
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This note was uploaded on 11/10/2011 for the course PT 101 taught by Professor Staff during the Spring '10 term at Texas State.

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