2020 Phase-2 Excretory Products and their EliminationCounter current mechanism in the nephron Medium Question 18 of 60 in Excretory Products and their Elimination

The increase in osmolarity from outer to inner medullary interstitium is maintained due to: (i) Close proximity between Henle's loop and vasa recta (ii) Counter current mechanism (iii) Selective secretion of $HCO_3^-$ and hydrogen ions in PCT (iv) Higher blood pressure in glomerular capillaries

A (i) and (ii)
B Only (ii)
C (iii) and (iv)
D (i), (ii) and (iii)

The answer is A.

Solution

The increasing osmolarity of the medullary interstitium (from outer to inner medulla) is maintained by the close anatomical proximity between the loop of Henle and the vasa recta (i), operating together via the counter current mechanism (ii). Statements (iii) and (iv) are unrelated to this specific mechanism.

Concept Counter current mechanism in the nephron

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60 questions from this chapter have appeared across 24 exam years.