Renal physiology: countercurrent mechanism: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Renal physiology: countercurrent mechanism

Sample item

What is the primary role of the loop of Henle in urine concentration?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Create a hyperosmotic medullary interstitium

The loop of Henle establishes the corticomedullary osmotic gradient through countercurrent multiplication. This gradient permits ADH-dependent water reabsorption from collecting ducts.

Option by option

  • A. Produce renin

    Renin is produced by juxtaglomerular cells.

  • B. Secrete aldosterone

    Aldosterone is produced by adrenal cortex.

  • C. Reabsorb all filtered glucose

    Glucose is largely reabsorbed in proximal tubule.

  • D. Create a hyperosmotic medullary interstitium (correct)

    Correct. The medullary gradient is essential for concentrating urine.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Create a hyperosmotic medullary interstitium. The loop of Henle establishes the corticomedullary osmotic gradient through countercurrent multiplication.

Why is "Produce renin" not the answer?

Renin is produced by juxtaglomerular cells.

Why is "Secrete aldosterone" not the answer?

Aldosterone is produced by adrenal cortex.

Why is "Reabsorb all filtered glucose" not the answer?

Glucose is largely reabsorbed in proximal tubule.

What concept does this question test?

It tests Renal physiology: countercurrent mechanism in Physiology. This gradient permits ADH-dependent water reabsorption from collecting ducts.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Renal physiology: countercurrent mechanism?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.