Concentration of the tubular filtrate by the countercurrent mechanism is dependent on all of the following except:
A) High salt concentration in the medulla
B) Water-impermeable walls of the ascending loop of Henle
C) Reabsorption of sodium and chloride from the ascending loop of Henle
D) Active transport reabsorption of sodium and glucose in the proximal convoluted tubule

Question

Quizplus · Accepted Answer

The active transport reabsorption of sodium and glucose in the proximal convoluted tubule is not directly involved in the countercurrent mechanism of concentration. The other options are all involved in the countercurrent mechanism. High salt concentration in the medulla creates an osmotic gradient, the water-impermeable walls of the ascending loop of Henle prevent the diffusion of water out of the tubule, and reabsorption of sodium and chloride from the ascending loop of Henle further concentrates the tubular filtrate.

Concentration of the Tubular Filtrate by the Countercurrent Mechanism Is