Respiratory system: compliance in emphysema: 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: compliance in emphysema

Sample item

A 62-year-old smoker with emphysema has a barrel-shaped chest. Which change in lung mechanics best explains his hyperinflation?

AStiffening of the chest wall alone pushes FRC upwardBLoss of elastic recoil raises lung compliance, so FRC rises to a larger volumeCIncreased lung elastic recoil lowers compliance, so FRC risesDRaised surfactant activity lowers surface tension and keeps alveoli expanded

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

The answer and the reasoning

B. Loss of elastic recoil raises lung compliance, so FRC rises to a larger volume

FRC is the volume at which the inward recoil of the lungs balances the outward recoil of the chest wall. In emphysema, destruction of elastic tissue lowers lung recoil and increases compliance, so the balance point moves to a greater volume and the chest becomes barrel shaped.

Option by option

A. Stiffening of the chest wall alone pushes FRC upward
Chest wall stiffness is not the primary lesion in emphysema.
B. Loss of elastic recoil raises lung compliance, so FRC rises to a larger volume (correct)
Reduced lung recoil shifts the equilibrium point to a higher FRC.
C. Increased lung elastic recoil lowers compliance, so FRC rises
Recoil is reduced in emphysema, and increased recoil lowers FRC, as in pulmonary fibrosis.
D. Raised surfactant activity lowers surface tension and keeps alveoli expanded
Surfactant is not increased in emphysema, and its main effect is on alveolar stability.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is B, Loss of elastic recoil raises lung compliance, so FRC rises to a larger volume. FRC is the volume at which the inward recoil of the lungs balances the outward recoil of the chest wall.

Why is "Stiffening of the chest wall alone pushes FRC upward" not the answer?

Chest wall stiffness is not the primary lesion in emphysema.

Why is "Increased lung elastic recoil lowers compliance, so FRC rises" not the answer?

Recoil is reduced in emphysema, and increased recoil lowers FRC, as in pulmonary fibrosis.

Why is "Raised surfactant activity lowers surface tension and keeps alveoli e…" not the answer?

Surfactant is not increased in emphysema, and its main effect is on alveolar stability.

What concept does this question test?

It tests Respiratory system: compliance in emphysema in Physiology. In emphysema, destruction of elastic tissue lowers lung recoil and increases compliance, so the balance point moves to a greater volume and the chest becomes barrel shaped.

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: compliance in emphysema?

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.