Question

During concentration of urine by the human kidneys, NaCl is returned to the medullary interstitium by the
(A) Descending limb of the loop of Henle
(B) Ascending limb of the loop of Henle
(C) Descending limb of the vasarecta
(D) Ascending limb of the vasarecta​

Answer 1

The answer is option B) Ascending limb of vasa recta.

Explanation:

• Vasa Recta is U-shaped minute vessel of efferent arteriole emerging from the glomerulus that runs parallel to the Henle's loop.
• NaCl is transported by the ascending limb of Henle which is exchanged with the descending branch od Vasa recta.
• NaCl is returned to the interstitium by ascending portion of Vasa recta.
• Both Vasa Recta and Loop of Henle helps in concentrating urine. The flow of filtrate in the two limbs of Henle's loop is in opposite directions and thus forms a counter current.