Question 17 Which of the following contributes directly to the generation of a hypertonic medullary interstitium in the kidney? Answers A - E A Active H2O reabsorption in the ascending limb of the loop of Henle B Active Na transport into the lumen of the descending limb of the loop of Henlo C. Water reabsorption in the cortical collecting duct D Active Na reabsorption in the distal convoluted tubule E Urea reabsorption from the inner medullary collecting duct.