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 is the main drive to ventilation in healthy adults?

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

The answer and the reasoning

B. Rise in arterial carbon dioxide

Central chemoreceptors respond mainly to carbon dioxide-related changes in cerebrospinal fluid pH, making increased arterial carbon dioxide a major ventilatory stimulus.

Option by option

  • A. Rise in hemoglobin

    Hemoglobin concentration does not directly provide the main drive.

  • B. Rise in arterial carbon dioxide (correct)

    Correct: rising CO2 is the main normal ventilatory drive.

  • C. Rise in oxygen

    Oxygen becomes more important at markedly low arterial levels.

  • D. Fall in serum sodium

    Serum sodium does not normally control ventilation.

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, Rise in arterial carbon dioxide. Central chemoreceptors respond mainly to carbon dioxide-related changes in cerebrospinal fluid pH, making increased arterial carbon dioxide a major ventilatory stimulus.

Why is "Rise in hemoglobin" not the answer?

Hemoglobin concentration does not directly provide the main drive.

Why is "Rise in oxygen" not the answer?

Oxygen becomes more important at markedly low arterial levels.

Why is "Fall in serum sodium" not the answer?

Serum sodium does not normally control ventilation.

What concept does this question test?

It tests Respiratory physiology in Physiology. The correct option holds because: Correct: rising CO2 is the main normal ventilatory drive.

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.