Renal: natriuretic peptide: 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: natriuretic peptide

Sample item

A patient in heart failure has raised atrial natriuretic peptide. Which arteriolar effect in the kidney contributes to the natriuresis?

AAfferent constriction with efferent dilatation, lowering GFRBDilatation of both arterioles, leaving GFR unchangedCAfferent dilatation with efferent constriction, raising GFRDConstriction of both arterioles, lowering renal blood flow

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

The answer and the reasoning

C. Afferent dilatation with efferent constriction, raising GFR

Atrial natriuretic peptide acts through cGMP to dilate the afferent and constrict the efferent arteriole, which increases glomerular capillary pressure and GFR. It also inhibits sodium reabsorption in the collecting duct and suppresses renin, aldosterone and ADH. The net effect is natriuresis and diuresis.

Option by option

A. Afferent constriction with efferent dilatation, lowering GFR
This pattern would reduce GFR and cause sodium retention.
B. Dilatation of both arterioles, leaving GFR unchanged
Equal dilatation would not preferentially raise capillary pressure.
C. Afferent dilatation with efferent constriction, raising GFR (correct)
Correct. The combination raises filtration pressure and filtered sodium.
D. Constriction of both arterioles, lowering renal blood flow
Constriction of both would reduce renal blood flow and sodium excretion.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Afferent dilatation with efferent constriction, raising GFR. Atrial natriuretic peptide acts through cGMP to dilate the afferent and constrict the efferent arteriole, which increases glomerular capillary pressure and GFR.

Why is "Afferent constriction with efferent dilatation, lowering GFR" not the answer?

This pattern would reduce GFR and cause sodium retention.

Why is "Dilatation of both arterioles, leaving GFR unchanged" not the answer?

Equal dilatation would not preferentially raise capillary pressure.

Why is "Constriction of both arterioles, lowering renal blood flow" not the answer?

Constriction of both would reduce renal blood flow and sodium excretion.

What concept does this question test?

It tests Renal: natriuretic peptide in Physiology. It also inhibits sodium reabsorption in the collecting duct and suppresses renin, aldosterone and ADH. The net effect is natriuresis and diuresis.

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: natriuretic peptide?

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.