Question

The osmotic gradient in the medullary region of the kidneys is established and maintained by which of the following?

1) Na⁺/K⁺/Cl⁻ cotransporters in the ascending limb of the loop of Henle
2) Na⁺/K⁺/Cl⁻ cotransporters in the descending limb of the loop of Henle
3) efflux of water from the ascending limb of the loop of Henle
4) efflux of water from the descending limb of the loop of Henle
5) efflux of Na⁺ from the descending limb of the loop of Henle

Answer 1

The osmotic gradient in the medullary region of the kidneys is established and maintained by the presence of Na+/K+/Cl- cotransporters in the ascending limb of the loop of Henle and the efflux of water from the descending limb.

Step-by-step explanation:

The osmotic gradient in the medullary region of the kidneys is established and maintained by several factors. One of the key factors is the presence of Na+/K+/Cl- cotransporters in the ascending limb of the loop of Henle. These cotransporters actively transport sodium, potassium, and chloride ions out of the filtrate, creating a concentration gradient.

Additionally, water permeability in the descending limb of the loop of Henle allows water to flow from the filtrate to the interstitial fluid, further concentrating the urine. This efflux of water helps in establishing and maintaining the osmotic gradient in the medullary region.