Question

ADH controls water permeability of

• A. Collecting tube/duct
• B. Proximal convoluted tube
• C. Distal convoluted tubule
• D. All the above

Answer 1

The correct option is A Collecting tube/duct

ADH or vasopressin is effective in reabsorption of water by changing permeability of DCT, collecting tubules and collecting ducts.

Water permeability and concentration of urine is controlled by vassopressin by regulating the reabsorption of water in the collecting tubule. It is known as antidiuretic hormone released by the posterior pituitary. It triggers the release of aldosterone which further increases the concentration of sodium ions in the blood. The increased salt concentration in the blood increases the blood osmotic potential which further increases the reabsorption of water into the collecting tubule and thus the urine released is the concentrated one. In the absence of vassopressin, the water absorption in the cllecting tubules is less so the urine produced is dilute one.

So, the correct answer is collecting duct'.