Question

Which of the following sentences about vasa recta is correct?

• A. It is a part of the renal tubule.
• B. It is a U-shaped vessel running parallel to loop of Henle deep into the medulla in most of the nephrons.
• C. It originates from the afferent arteriole.
• D. During the counter-current mechanism, NaCl is transported back to the interstitium by the ascending portion of vasa recta.

Answer 1

Answer: (D)

During the counter-current mechanism, NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of vasa recta. NaCl is returned to the interstitium by the ascending portion of vasa recta.
The efferent arteriole emerging from the glomerulus forms a fine capillary network around the renal tubule called the peritubular capillaries. A minute vessel of this network runs parallel to the Henle’s loop forming a ‘U’ shaped vasa recta. Vasa recta is absent or highly reduced in cortical nephrons.