Question

Assertion (A) Vasa recta is a minute vessel running parallel to loop of Henle.
Reason (R) It plays a very important role in concentrating the urine.

• A. If both A and R are true and R is the correct explanation of A
• B. If both A and R are true, but R is not the correct explanation of A
• C. If A is true, but R is false
• D. If A is false, but R is true

Answer 1

Answer: (A)

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Vasa recta is a minute vessel network that runs parallel to the Henle's loop forming a ' $U$ '-shaped structure. This structural arrangement helps in concentration of urine, as these faciliate counter-current mechanism. The counter-current mechanism helps to maintain a concentration gradient in the medullary interstitium.
Presence of such interstitial gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine).