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 role of pulmonary surfactant?

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

The answer and the reasoning

C. Reduce alveolar surface tension

Surfactant lowers surface tension at the air-liquid interface in alveoli, improving compliance and helping prevent collapse of small alveoli during expiration; deficiency is especially important in premature neonates.

Option by option

  • A. Transport carbon dioxide in erythrocytes

    Most carbon dioxide transport is through bicarbonate formation, not surfactant.

  • B. Stimulate diaphragm contraction

    Diaphragm contraction is controlled by neural motor input.

  • C. Reduce alveolar surface tension (correct)

    Correct: surfactant reduces surface tension and stabilizes alveoli.

  • D. Increase airway mucus viscosity

    Increased mucus viscosity would impair airflow rather than describe surfactant action.

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 C, Reduce alveolar surface tension. Surfactant lowers surface tension at the air-liquid interface in alveoli, improving compliance and helping prevent collapse of small alveoli during expiration; deficiency is especially important in premature neonates.

Why is "Transport carbon dioxide in erythrocytes" not the answer?

Most carbon dioxide transport is through bicarbonate formation, not surfactant.

Why is "Stimulate diaphragm contraction" not the answer?

Diaphragm contraction is controlled by neural motor input.

Why is "Increase airway mucus viscosity" not the answer?

Increased mucus viscosity would impair airflow rather than describe surfactant action.

What concept does this question test?

It tests Respiratory physiology in Physiology. The correct option holds because: Correct: surfactant reduces surface tension and stabilizes alveoli.

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.