During countercurrent mechanisms, which of the following area of nephron does filtrate become hypertonic to plasma?

 # During countercurrent mechanisms, which of the following area of nephron does filtrate become hypertonic to plasma?

A. Bowman’s capsule

B. Proximal convoluted tubule

C. Loop of Henle

D. Distal convoluted tubule

The correct answer is C. Loop of Henle.

A circuit of fluid in the loop of Henle—an important part of the kidneys—allows for gradual buildup of the concentration of urine in the kidneys, by using active transport on the exiting nephrons (tubules carrying liquid in the process of gradually concentrating the urea). The active transport pumps need only to overcome a constant and low gradient of concentration, because of the countercurrent multiplier mechanism.