NEETZoology-Excretory Products and their Elimination

NEET Zoology Counter Current Mechanism MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Mechanism of concentration of the filtrate occurs in following steps:

(A) NaCl is transported by the ascending limb of Henle's loop which is exchanged with the descending limb of vasa recta.

(B) NaCl is returned to the interstitium by the ascending portion of vasa recta.

(C) Small amounts of urea enter the thin segment of the ascending limb of Henle's loop which is transported back to the interstitium by the collecting tubule.

(D) This mechanism helps to maintain a concentration gradient in the medullary interstitium. From above phenomena, following conclusions are drawn:

A

Two correct and one wrong

B

One correct and two wrong

C

All three wrong

D

All three correct

Correct Answer

Option 4

Detailed Explanation

The above described transport of substances facilitated by the special arrangement of Henle's loop and vasa recta is called the counter current mechanism. This 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).

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