Parathormone increases calcium absorption by acting at ?: (A) PCT, (B) DCT, (C) Loop of henle, (D) Collecting duct
Answer is B. Ans. is 'b' i.e., DCT ParatharmoneParatharmone is 84 aminoacid polypeptide hormone secreted from parathyroid glands.Its secretion is regulated by plasma Ca++ concentration -- fall in Ca++ concentration increases the secretion of paratharmone.ActionsPTH increases resorption of calcium from bone - most prominant action.PTH increases calcium reabsorption from distal tubules of kidney.PTH decreases phophate reabsorption from proximal tubules of kidney.PTH has no direct effect on calcium absorption from intestine but increases it indirectly by enhancing the formation of calcitriol by activating la-hydroxylose.PTH decreases calcium level in milk, saliva, and ocular lens -- may be responsible for development of cataract in hypothyroidism.