Which choice describes the countercurrent mechanism of the nephron loop?
A)Water moves out of the ascending limb; sodium moves into the ascending limb
B)Water moves into the ascending limb; sodium moves out of the ascending limb
C)Water moves out of the descending limb; sodium moves out of the ascending limb
D)Water moves into the descending limb; sodium moves out of the descending limb

Question

Quizplus · Accepted Answer

The countercurrent mechanism of the nephron loop involves water moving out of the descending limb and sodium moving out of the ascending limb in opposite directions, creating a concentration gradient that allows for maximal reabsorption of water and solutes from the urine. Choice A and B are incorrect because they describe sodium and water moving in the same direction, which would not create the necessary concentration gradient. Choice D is incorrect because it describes sodium and water moving in opposite directions in the descending limb, which is not part of the countercurrent mechanism.

Which Choice Describes the Countercurrent Mechanism of the Nephron Loop