Question

Study the following

(a) Proximal convoluted tube
(b) Descending limb of Henle's loop
(c) Distal convoluted tube
(d) Ascending limb of Henle's loop
(e) Collecting Tubule

Where does facultative reabsorption of water take place?

• A. a, b
• B. c, d, e
• C. e
• D. a, b and e

Answer 1

The correct option is C e

Obligatory water reabsorption: eighty-five percent of the water reabsorption occurs irrespective of the body water balance and is called obligatory (must occur) about 65% of the obligatory reabsorption occurs in proximal tubules and 20% of the obligatory reabsorption occurs in distal tubules. The remaining 15% of water may or may not be reabsorbed depending on the body's water balance. It is called facultative reabsorption (optional). The facultative reabsorption occurs from the collecting tubule as it courses through the renal medulla. It is under the control of the antidiuretic hormone (ADH) which controls the permeability of the collecting tubule to water.

So, the correct answer is 'Collecting tubule'.