Respiratory system: work of breathing: 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: work of breathing

Sample item

Patients with pulmonary fibrosis breathe rapidly and shallowly. What is the physiological advantage of this pattern?

ASmaller tidal volumes reduce the elastic work done against stiff lungsBShallow breaths raise alveolar ventilation per minuteCA rapid rate increases surfactant release and lung complianceDFaster airflow reduces turbulent resistive work in the airways

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

The answer and the reasoning

A. Smaller tidal volumes reduce the elastic work done against stiff lungs

In restrictive disease the lungs are stiff, so the elastic component of the work of breathing is large and rises with tidal volume. Taking smaller, more frequent breaths minimises the total work. In obstructive disease the opposite pattern, slow deep breathing, reduces the resistive work.

Option by option

A. Smaller tidal volumes reduce the elastic work done against stiff lungs (correct)
Correct. Shallow breathing minimises elastic work in a stiff lung.
B. Shallow breaths raise alveolar ventilation per minute
Shallow breaths increase the proportion of each breath wasted as dead space and do not raise alveolar ventilation.
C. A rapid rate increases surfactant release and lung compliance
Surfactant release is stimulated by deep breaths and sighs rather than shallow rapid breathing.
D. Faster airflow reduces turbulent resistive work in the airways
Faster airflow raises resistive work and the problem here is elastic.

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 A, Smaller tidal volumes reduce the elastic work done against stiff lungs. In restrictive disease the lungs are stiff, so the elastic component of the work of breathing is large and rises with tidal volume.

Why is "Shallow breaths raise alveolar ventilation per minute" not the answer?

Shallow breaths increase the proportion of each breath wasted as dead space and do not raise alveolar ventilation.

Why is "A rapid rate increases surfactant release and lung compliance" not the answer?

Surfactant release is stimulated by deep breaths and sighs rather than shallow rapid breathing.

Why is "Faster airflow reduces turbulent resistive work in the airways" not the answer?

Faster airflow raises resistive work and the problem here is elastic.

What concept does this question test?

It tests Respiratory system: work of breathing in Physiology. Taking smaller, more frequent breaths minimises the total work. In obstructive disease the opposite pattern, slow deep breathing, reduces the resistive work.

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 Respiratory system: work of breathing?

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.