Question
Which of the following is impermeable to water?
Vertical limb of loop of Henle
Descending limb of loop of Henle
Ascending limb of loop of Henle
Both 'a' and 'b'
Solution
C.
Ascending limb of loop of Henle
Ascending limb of loop of Henle has two, characteristics.
(i) It actively pumps Na+ and Cl- into the surrounding tissue fluid in the medulla.
(ii) It is impermeable to water, and partialy permeable to urea. This is because in the thick ascending limb, there is active reabsorption of ions. As a result, these cells can make the interstitial fluid hyperosmotic relative to the fluid inside the tubule (the filtrate).
