PHYS20008 Lecture Notes - Lecture 24: Active Transport, Peritubular Capillaries, Reabsorption
25 May 2019
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Document Summary
To calculate clearance rates, find out how much plasma volume would need to be excreted for the urine concentrations and plasma concentrations to match up. Sodium has to be actively pumped using a potassium sodium pump to move sodium into the ecf then absorbed by peritubular capillary. Sodium has to move across the epithelium of the tube first. Anions then follow the sodium charge gradient. Now that it is a dilute tube water follows anions across. Other solutes still in the tube follow the water due to the gradient. Ie one primary active transport causes lots of secondary transport (still considered active) The luminal side of the tubular epithelium has an enac to let the sodium passively move in. The active sodium potassium pump sits on the ecf side of the tubular epithelium and moves the sodium across to the ecf and peritubular capillary. Glucose and amino acids use cotransporters to attach to the sodium and use the sodium gradient.
