Vasa recta

Definition

The vasa recta are a series of straight capillaries in the medulla of the kidney that run parallel to the loop of Henle. They play a critical role in the concentration and dilution of urine by participating in the counter-current exchange mechanism.

Related terms

Loop of Henle:

A long, U-shaped portion of a tubule in the kidney that plays an essential role in concentrating urine and conserving water.

Counter: current exchange - A mechanism by which fluids flow in opposite directions through adjacent parallel pathways, enabling efficient transfer or exchange of heat or solutes.

Medulla: The innermost part of the kidney, which contains the nephrons' loops of Henle and is essential for urine concentration