Respiratory system: hypoxic pulmonary vasoconstriction: 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.

Try it

Physiology · Respiratory system: hypoxic pulmonary vasoconstriction

Sample item

A man with chronic bronchitis has long-standing alveolar hypoxia and develops right-sided heart failure. Which mechanism links the two?

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

The answer and the reasoning

C. Hypoxic pulmonary vasoconstriction raises pulmonary vascular resistance and right ventricular afterload

In the lung, low alveolar PO2 constricts the local precapillary arterioles, diverting blood to better ventilated regions and so protecting V/Q matching. When hypoxia is generalised, as in chronic bronchitis or at altitude, the effect is widespread and sustained, causing pulmonary hypertension, right ventricular hypertrophy and cor pulmonale.

Option by option

  • A. Hypoxia constricts systemic arteries, raising left ventricular afterload and left atrial pressure

    Systemic arteries tend to dilate in hypoxia, and the pulmonary circulation is the one that constricts.

  • B. Hypoxia raises pulmonary capillary oncotic pressure, causing oedema and right heart strain

    Pulmonary hypertension in chronic hypoxia is not caused by a change in capillary oncotic pressure.

  • C. Hypoxic pulmonary vasoconstriction raises pulmonary vascular resistance and right ventricular afterload (correct)

    Widespread vasoconstriction in the lung increases the pressure load on the right ventricle.

  • D. Hypoxia dilates pulmonary arterioles, so a large flow overloads the right ventricle

    Hypoxia constricts pulmonary vessels, the opposite of systemic vessels, and does not dilate them.

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.

More Physiology questions

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Hypoxic pulmonary vasoconstriction raises pulmonary vascular resistance and right ventricular afterload. In the lung, low alveolar PO2 constricts the local precapillary arterioles, diverting blood to better ventilated regions and so protecting V/Q matching.

Why is "Hypoxia constricts systemic arteries, raising left ventricular afterl…" not the answer?

Systemic arteries tend to dilate in hypoxia, and the pulmonary circulation is the one that constricts.

Why is "Hypoxia raises pulmonary capillary oncotic pressure, causing oedema a…" not the answer?

Pulmonary hypertension in chronic hypoxia is not caused by a change in capillary oncotic pressure.

Why is "Hypoxia dilates pulmonary arterioles, so a large flow overloads the r…" not the answer?

Hypoxia constricts pulmonary vessels, the opposite of systemic vessels, and does not dilate them.

What concept does this question test?

It tests Respiratory system: hypoxic pulmonary vasoconstriction in Physiology. When hypoxia is generalised, as in chronic bronchitis or at altitude, the effect is widespread and sustained, causing pulmonary hypertension, right ventricular hypertrophy and cor pulmonale.

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 system: hypoxic pulmonary vasoconstriction?

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.