2,232
edits
Changes
Aquaporins of the Kidney and Water Homeostasis - Anatomy & Physiology (view source)
Revision as of 13:42, 5 July 2008
, 13:42, 5 July 2008→What are Aquaporins
* Family of membrane channel proteins
* Family of membrane channel proteins
* Over a dozen homologous water transporting proteins make up this family in mammals
* Over a dozen homologous water transporting proteins make up this family in mammals
* Allow rapid transport of water accross membranes
* Allow rapid transport of substances accross membranes
* Found in all life forms
* Found in all life forms
* Commonly abbreviated to '''AQP'''
* Commonly abbreviated to '''AQP'''
* Ones found in the kidneys are:
* Ones found in the kidneys are:
** AQP1 - Tubules
** <Font Color="#669933">'''AQP1'''</Font> - Tubules
** AQP2 - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** <Font Color="#669933">'''AQP2'''</Font> - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** AQP3 - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** <Font Color="#CC6633">'''AQP3'''</Font> - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** AQP4 - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** <Font Color="#669933">'''AQP4'''</Font> - [[Collecting Duct - Anatomy & Physiology| Collecting duct]]
** AQP6 - [[Collecting Duct - Anatomy & Physiology| Collecting duct (intercalated cells)]]
** <Font Color="#660000">'''AQP6'''</Font> - [[Collecting Duct - Anatomy & Physiology| Collecting duct (intercalated cells)]]
** AQP 7 - [[Proximal Tubule - Anatomy & Physiology| Proximal tubule]]
** <Font Color="#CC6633">'''AQP7'''</Font> - [[Proximal Tubule - Anatomy & Physiology| Proximal tubule]]
** AQP11 - Kidney
** <Font Color="#9900ff">'''AQP11'''</Font> - Kidney
* They are colour coded according to their function
* They are colour coded according to their function
** <Font Color="#669933">Water channels</Font>
** <Font Color="#669933">'''Water channels'''</Font>
** <Font Color="#CC6633">Glycerol channels</Font>
** <Font Color="#CC6633">'''Glycerol channels'''</Font>
** <Font Color="#660000">Intracellular chloride channels</Font>
** <Font Color="#660000">'''Intracellular chloride channels'''</Font>
** <Font Color="#9900ff">Function Unknown</Font>
** <Font Color="#9900ff">'''Function Unknown'''</Font>
==Function==
* They allow the reabsorption of water, glycerol and chlorine from the filtrate
* Without the water ones producing concentrated urine would be impossible
* AQP2 is stored in vesicle membranes within the [[Collecting Duct - Anatomy & Physiology #Principal Cells| principal cells]] of the [[Collecting Duct - Anatomy & Physiology| collecting ducts]]
* [[Useful definitions - Renal Anatomy & Physiology| ADH]] causes these vesicles to attach to the principal cell membranes.
* This is how ADH works.
** The higher its concentration the more AQP2 avaiable to water within the collecting duct
** The more water is reabsorbed
** Thanks to the gradient created by the hypertonic medulla which is present due to the countercurrent multiplier in the [[Loop Of Henle - Anatomy & Physiology| Loop of Henle]]
* This system allows both concentrated and dilute urine to be produced depending on ADH secretion and therefore the density of aquaporins in the principal cell membranes
==Why Do We Need Aquaporins==
==Why Do We Need Aquaporins==
* Contrary to popular belief diffusion of water accross lipid bilayers is too slow for most physiological processes
* Contrary to popular belief diffusion of water accross lipid bilayers is too slow for most physiological processes
* Aquaporins solve this problem
* Aquaporins solve this problem