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Aquaporins of the Kidney and Water Homeostasis - Anatomy & Physiology (view source)
Revision as of 11:11, 15 August 2008
, 11:11, 15 August 2008→[[Endocrine System - Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland| ADH]] and the [[Collecting Duct - Anatomy & Physiology|Collecting Duct]]
==[[Endocrine System - Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland| ADH]] and the [[Collecting Duct - Anatomy & Physiology|Collecting Duct]]==
==[[Endocrine System - Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland| ADH]] and the [[Collecting Duct - Anatomy & Physiology|Collecting Duct]]==
The membrane of the [[Collecting Duct - Anatomy & Physiology|Collecting Duct]] is practically impermeable to water. Therefore in order for water reabsorbtion from this part of the nephron to occur it is vital that aquaporins are inserted. This is the role of [[Endocrine System - Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland| ADH]]. These channels are always present on the basolateral membrane of the epithelial cells but their presence and concentration on the apical membrane is reliant on the concentration of ADH in the blood. ADH works by binding to V<sub>2</sub> receptors on the basolateral membranes of the cells and activates adenyl cyclase creating cyclicAMP (cAMP). This causes vesicles with ready made glycoprotein '''AQP2''' aquaporins in their membranes to move to the apical cell membrane and insert the aquaporins via exocytosis. This rapidly increases the water permeability and allowing reabsorption
The membrane of the [[Collecting Duct - Anatomy & Physiology|Collecting Duct]] is practically impermeable to water. Therefore in order for water reabsorbtion from this part of the nephron to occur it is vital that aquaporins are inserted. This is the role of [[Endocrine System - Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland| ADH]]. These channels are always present on the basolateral membrane of the epithelial cells but their presence and concentration on the apical membrane is reliant on the concentration of ADH in the blood. ADH works by binding to '''V<sub>2</sub>''' receptors on the basolateral membranes of the cells and activates adenyl cyclase creating '''cyclicAMP''' (cAMP) this in turn activates '''protein kinase A''' which causes '''protein phosphorylation'''. This causes vesicles with ready made glycoprotein '''AQP2''' aquaporins in their membranes to move to the apical cell membrane and insert the aquaporins via exocytosis. This rapidly increases the water permeability and allowing reabsorption
==Species Variation of the Ability to Conserve Water==
==Species Variation of the Ability to Conserve Water==