Why must the kidneys establish a concentration gradient in the interstitial fluid of the renal medulla in order to produce concentrated urine?

Video transcript

Everyone. Let's take a look at this question together. How does the descending loop of Henley contribute to urine concentration? Is it answer choice? A absorbing more sodium ions? Answer choice B allowing the water to pass but not the salutes. Answer choice. C reabsorbing the majority of chlorine or answer choice. All of the above. Let's work this problem out together to try to figure out which of the following answer choices best explains how the descending loop of Henley contributes to urine concentration. So in order to solve this question, we have to recall what we have learned about the descending loop of Henley and what would affect urine concentration. And we know that the descending loop of Henley allows water to pass out of the tubule into the surrounding interstitial fluid. And we also know that due to the permeability characteristics of the descending limb, it does. So while minimizing the movement of solutes, so the descending loop of Henley allows water to pass out of the tubule into that surrounding interstitial fluid while minimum the movement of the salutes and it does so due to the permeability characteristics of the descending limb, since that surrounding interstitial fluid is hypertonic or concentrated. So it moves the water out while minimizing the movement of salutes. Making answer choice B allowing the water to pass but not the salutes, the correct answer and all other answer choices are incorrect. I hope you found this video to be helpful. Thank you and goodbye.