What is the function of the vasa recta?

The function of the vasa recta is to surround the nephron as part of the blood supply. The vasa recta refers to the capillary network that extends from the arterioles into the medulla of the kidney, particularly around the loop of Henle in the nephron. This arrangement is crucial for maintaining the osmotic gradient in the medulla, which is essential for the concentration of urine.

As the nephron processes filtrate to form urine, the vasa recta plays a key role in the countercurrent exchange mechanism. It helps to reabsorb water and solutes, ensuring that nutrients and water are returned to the bloodstream while concentrating waste products in the urine. This close proximity allows for efficient exchange of substances without disrupting the osmotic balance maintained by the renal medulla, ultimately facilitating efficient urine concentration.

In contrast, while other options describe processes or structures associated with the kidney or urinary system, they do not accurately convey the specific role of the vasa recta in blood supply to the nephron.