Respiratory system: lung volumes in obesity: 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: lung volumes in obesity

Sample item

A 40-year-old man with a body mass index of 42 undergoes spirometry and lung volume measurement. Which pair of changes is typical?

AIncreased residual volume with air trappingBReduced expiratory reserve volume and functional residual capacityCIncreased total lung capacityDMarkedly reduced FEV1/FVC ratio

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

The answer and the reasoning

B. Reduced expiratory reserve volume and functional residual capacity

Mass loading of the chest wall and abdomen reduces chest wall compliance and pushes the diaphragm upward. The resting end-expiratory level falls, so expiratory reserve volume and functional residual capacity are reduced. The FEV1/FVC ratio is usually preserved because the process is restrictive.

Option by option

A. Increased residual volume with air trapping
Residual volume is usually preserved and air trapping is a feature of obstruction.
B. Reduced expiratory reserve volume and functional residual capacity (correct)
Correct. Chest wall loading reduces FRC, largely at the expense of expiratory reserve volume.
C. Increased total lung capacity
Total lung capacity is normal or mildly reduced, and not increased.
D. Markedly reduced FEV1/FVC ratio
The ratio is preserved in obesity because the airways are not primarily obstructed.

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, Reduced expiratory reserve volume and functional residual capacity. Mass loading of the chest wall and abdomen reduces chest wall compliance and pushes the diaphragm upward.

Why is "Increased residual volume with air trapping" not the answer?

Residual volume is usually preserved and air trapping is a feature of obstruction.

Why is "Increased total lung capacity" not the answer?

Total lung capacity is normal or mildly reduced, and not increased.

Why is "Markedly reduced FEV1/FVC ratio" not the answer?

The ratio is preserved in obesity because the airways are not primarily obstructed.

What concept does this question test?

It tests Respiratory system: lung volumes in obesity in Physiology. The resting end-expiratory level falls, so expiratory reserve volume and functional residual capacity are reduced. The FEV1/FVC ratio is usually preserved because the process is restrictive.

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: lung volumes in obesity?

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.