Question

The facultative absorption of water in the DCT and collecting duct takes place due to the secretion of ___________.

• A. TCT
• B. ACTH
• C. PTH
• D. ADH

Hint:

ADH increases water reabsorption and helps concentrate urine.

Answer 1

The Correct Option is D

Step 1: Understanding facultative reabsorption.
Facultative reabsorption of water refers to the regulated absorption of water depending on the body’s hydration status.
Step 2: Role of ADH.
Antidiuretic hormone (ADH), also called vasopressin, increases the permeability of the distal convoluted tubule (DCT) and collecting duct to water.
This allows more water to be reabsorbed into the bloodstream when required.
Step 3: Analysis of options.
(A) TCT: Incorrect — it is a tubule, not a hormone.
(B) ACTH: Incorrect — regulates adrenal cortex hormones.
(C) PTH: Incorrect — regulates calcium and phosphate balance.
(D) ADH: Correct — controls facultative water reabsorption.
Step 4: Conclusion.
Facultative absorption of water in the DCT and collecting duct occurs due to the secretion of ADH.