Question

what is the response of cells in the collecting tubules in the nephrons when ADH is secreted?

Answer 1

ADH is antidIuretic hormone made by the hypothalamus.This play important role in the control of the body’s osmotic balance and regulation blood pressure.ADH secretion effects the permeability of cells in the collecting tubules and there by increase water reabsorption in kidney nephrons It  binds to the V receptor on these principle cells coupled to G. This binding leads to G activation of adenylate cyclase. This causes  increase in the second messenger cyclic AMP . An intracellular phosphorylation cascade is activated by protein kinase A which was activated by cAMP  .The phosphorylation of intracellular aquaporin-2 (AQP2) promotes the passive movement of water into the cells by their insertion into the apical membrane.This movement is guided by the  osmotic gradient established by NaCl and Urea This allows our body to conserve water in times of dehydration by secretion of concentrated or diluted urine.