Respiratory system: chronic mountain sickness: 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 system: chronic mountain sickness

Sample item

A 45-year-old man who has lived at 4,000 metres for 20 years has headache, cyanosis, a haematocrit of 72 percent and low arterial saturation. Which process explains the picture?

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

The answer and the reasoning

A. Loss of ventilatory acclimatisation with persistent hypoxaemia driving excess erythropoietin

In chronic mountain sickness (Monge's disease) ventilation becomes blunted and hypoxaemia persists. Sustained erythropoietin drive causes excessive polycythaemia, which raises blood viscosity and pulmonary pressure. Symptoms improve on descent.

Option by option

  • A. Loss of ventilatory acclimatisation with persistent hypoxaemia driving excess erythropoietin (correct)

    Correct. Under-ventilation sustains hypoxaemia, so erythropoietin keeps driving red cell production.

  • B. Overproduction of surfactant raising lung compliance

    Surfactant is not involved in this disorder.

  • C. Excess ventilation causing severe respiratory alkalosis

    The problem is inadequate ventilation, not over-ventilation.

  • D. Reduced erythropoietin because of renal hyperoxia

    Erythropoietin is raised, not reduced, by hypoxia.

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 A, Loss of ventilatory acclimatisation with persistent hypoxaemia driving excess erythropoietin. In chronic mountain sickness (Monge's disease) ventilation becomes blunted and hypoxaemia persists.

Why is "Overproduction of surfactant raising lung compliance" not the answer?

Surfactant is not involved in this disorder.

Why is "Excess ventilation causing severe respiratory alkalosis" not the answer?

The problem is inadequate ventilation, not over-ventilation.

Why is "Reduced erythropoietin because of renal hyperoxia" not the answer?

Erythropoietin is raised, not reduced, by hypoxia.

What concept does this question test?

It tests Respiratory system: chronic mountain sickness in Physiology. Sustained erythropoietin drive causes excessive polycythaemia, which raises blood viscosity and pulmonary pressure. Symptoms improve on descent.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: chronic mountain sickness?

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.