Respiratory physiology: 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 · Respiratory physiology

Sample item

What mechanism matches perfusion to ventilation in the lung?

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

The answer and the reasoning

B. Hypoxic pulmonary vasoconstriction

Hypoxic pulmonary vasoconstriction diverts blood away from poorly ventilated alveoli toward better ventilated regions, improving ventilation-perfusion matching.

Option by option

  • A. Renal autoregulation

    Renal autoregulation maintains kidney blood flow, not lung perfusion matching.

  • B. Hypoxic pulmonary vasoconstriction (correct)

    Correct: pulmonary hypoxia causes local vasoconstriction to improve matching.

  • C. Gag reflex

    Gag reflex protects the airway but does not regulate pulmonary vessels.

  • D. Systemic vasodilation

    Systemic vasodilation is not the local pulmonary matching mechanism.

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 B, Hypoxic pulmonary vasoconstriction. Hypoxic pulmonary vasoconstriction diverts blood away from poorly ventilated alveoli toward better ventilated regions, improving ventilation-perfusion matching.

Why is "Renal autoregulation" not the answer?

Renal autoregulation maintains kidney blood flow, not lung perfusion matching.

Why is "Gag reflex" not the answer?

Gag reflex protects the airway but does not regulate pulmonary vessels.

Why is "Systemic vasodilation" not the answer?

Systemic vasodilation is not the local pulmonary matching mechanism.

What concept does this question test?

It tests Respiratory physiology in Physiology. The correct option holds because: Correct: pulmonary hypoxia causes local vasoconstriction to improve matching.

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 Respiratory physiology?

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.