<prompt> In the nephrons, the vasopressin mainly acts at the level ofProximal convoluted tubulesDistal convoluted tubulesLoop of HenleCollecting tubules  <response>: Ans. d Collecting tubules; Ref. Guyton, Physiology, 10th ed., 773HORMONES ACTING ON KIDNEY HormonesStimulus for secretionActions on kidneys1Vasopressin ADHPlasma osmolalityBlood volumeH2O permeability of principal cells incollecting ducts.Urea absorption in collecting duct.NaK2CI-transporter in thick ascending limb.2AldosteroneBlood volume via Allplasma KNa re-absorption,Ksecretion, H secretion in distal tubule.3Angiotensin II Blood volume Via renin Contraction of efferent arteriole GFR,Na HCO3 re-absorption in PCT.4Atrial natriureticpeptide ANPAtrial pressureNa reabsorptionGFR5PTH-Plasma Ca2Ca2 reabsorption, PO43-reabsorption, 1,25OH2 vitamin D production 