Acid-base physiology: respiratory compensation: 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 · Acid-base physiology: respiratory compensation

Sample item

A patient has metabolic acidosis from diabetic ketoacidosis. Which respiratory response is expected?

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

The answer and the reasoning

D. Reduced arterial PCO2 from hyperventilation

Metabolic acidosis stimulates ventilation, lowering PCO2 and partially restoring pH. Kussmaul respiration is the conspicuous deep breathing pattern in severe ketoacidosis.

Option by option

  • A. No change in ventilation

    Chemoreceptor drive changes ventilation substantially in metabolic acidosis.

  • B. Increased bicarbonate secretion by lungs

    Lungs regulate carbon dioxide, not direct bicarbonate secretion.

  • C. Increased arterial PCO2 from hypoventilation

    Hypoventilation would retain carbon dioxide and worsen acidaemia.

  • D. Reduced arterial PCO2 from hyperventilation (correct)

    Correct. Hyperventilation compensates by removing carbon dioxide.

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 D, Reduced arterial PCO2 from hyperventilation. Metabolic acidosis stimulates ventilation, lowering PCO2 and partially restoring pH.

Why is "No change in ventilation" not the answer?

Chemoreceptor drive changes ventilation substantially in metabolic acidosis.

Why is "Increased bicarbonate secretion by lungs" not the answer?

Lungs regulate carbon dioxide, not direct bicarbonate secretion.

Why is "Increased arterial PCO2 from hypoventilation" not the answer?

Hypoventilation would retain carbon dioxide and worsen acidaemia.

What concept does this question test?

It tests Acid-base physiology: respiratory compensation in Physiology. Kussmaul respiration is the conspicuous deep breathing pattern in severe ketoacidosis.

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 Acid-base physiology: respiratory compensation?

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.