Which of the following statements concerning the loop of Henle of juxtamedullary nephrons is correct? A) the ascending limb of the loop of Henle is freely permeable to H₂O and NaCl. B) the filtrate is isotonic as it enters the loop of Henle, hypertonic at the tip of the loop, and hypotonic as it leaves the loop of Henle. C) the descending limb of the loop of Henle actively transports NaCl out of the tubule into the interstitial fluid. D) all of these answers. E) none of these answers.

Question

Quizplus · Accepted Answer

The descending limb of the loop of Henle is permeable to water and not solutes, so as water leaves, the filtrate becomes more concentrated, making it hypertonic at the tip of the loop. As the filtrate ascends up the loop, the ascending limb is impermeable to water, but permeable to solutes (specifically NaCl). This creates a concentration gradient where the interstitial fluid surrounding the loop is hypertonic and the filtrate is hypotonic as it leaves the loop. Therefore, choice B is the correct statement. Choices A and C are incorrect as the ascending limb is only permeable to NaCl, not H₂O and the descending limb passively reabsorbs water, not actively transports NaCl. Choice D is also incorrect as only statement B is accurate.

Which of the Following Statements Concerning the Loop of Henle