Question

Statement-1: The final reabsorption of water from the urine into the blood occurs through the collecting duct of a mammalian nephron resulting in thhe production of hyperosmotic urine.
Statement-2: The loop of henle creates a sodium gradient in the interstitial fluid.
A. both statements 1 and 2 are correct.
B. Statement 1 is correct but statement 2 is incorrect
C. Statement 1 is incorrect but statement 2 is correct
D. Both statements 1 and 2 are incorrect.

Answer 1

Correct Answer - A
The couter current mechanism in loop of Henle and vasa recta, helps in maintaining an increasing osmolarity of the interstitial fluid i.e., from 300 mOs mol `L^(-1)` in the cortex to about 1200 mOsmol `L^(-1)` in the inner medulla. This gradient is mainly caused by NaCl and urea. This gradient thus helps in easy reabsorption of water from the filtrate in the collecting duct so as to produce hyperosmotic urine.