Question

Water leaves the nephron and enters the interstitial space because which of the following is true?

A. Water is co-transported with solutes.
B. Water goes from an area of high osmolarity to low osmolarity.
C. Water goes from an area of low osmolarity to high osmolarity.
D. Water goes from an area of low concentration to an area of high concentration.

Answer 1

In the loop of Henle, water flows from the filtrate to the interstitial fluid. Osmolality in the descending limb increases, while water is actively transported out in the ascending limb.

Step-by-step explanation:

d. The descending limb of the loop of Henle is water permeable, so the water flows from the filtrate to the interstitial fluid. Osmolality in the limb increases, and it is higher inside the loop than in the interstitial fluid. As the filtrate enters the ascending limb, Na* and Cl- ions exit through ion channels present in the cell membrane. Further up, sodium is actively transported out of the filtrate, and chlorine ions follow.