BIOM20002 Lecture Notes - Lecture 64: Sodium-Glucose Transport Proteins, Tight Junction, Reabsorption
Document Summary
Tubular reabsorption greater than secretion - hence how 200l filtered into 2l daily. Reabsorption greatest at the proximal tubule and gradually decreases along the way. Body absorbs most of the fluid back asap - bulk processing occurs first. Reabsorbing this allows you to reabsorb the others and secrete out h+ Basolateral surface of tubular cells has a very small gap. Na reabsorbed by secondarily active transport (it is actually passive down a conc gradient). The primary active transporter is the na/k atpase pump in the basolateral membrane - pumps na out to ecf (reabsorbed into peritubular capillaries) and k into cell. Conc gradient draws na in from apical surface. Na/h counter transporter - na in and h+ out. The h+ is not excreted used to bind bicarbonate and bring it back into blood. Pumping na+ into ecf causes anions to become attracted to ecf. These can go through cell membrane or tight junctions.
