Respiratory system: control 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: control of breathing

Sample item

In an animal experiment, the brainstem is cut at the mid-pontine level and both vagi are severed. The animal now takes prolonged inspiratory gasps with brief expiration. Which influence has been removed?

AInspiratory drive from the dorsal respiratory groupBRhythm generation by the pre-Botzinger complexCInhibition of inspiration by the pneumotaxic centreDChemoreceptor input from the carotid body

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

The answer and the reasoning

C. Inhibition of inspiration by the pneumotaxic centre

The pneumotaxic centre in the upper pons switches off inspiration, and vagal stretch afferents add to this. Removing both leaves the apneustic centre unopposed, producing apneustic breathing with sustained inspiration. The medullary groups remain intact.

Option by option

A. Inspiratory drive from the dorsal respiratory group
The dorsal respiratory group lies in the medulla and still drives inspiration.
B. Rhythm generation by the pre-Botzinger complex
The pre-Botzinger complex lies in the medulla and is intact after a pontine cut.
C. Inhibition of inspiration by the pneumotaxic centre (correct)
Correct. Loss of pneumotaxic and vagal inhibition leaves inspiration unchecked.
D. Chemoreceptor input from the carotid body
Carotid body input is carried by the glossopharyngeal nerve and is unaffected by this lesion.

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 C, Inhibition of inspiration by the pneumotaxic centre. The pneumotaxic centre in the upper pons switches off inspiration, and vagal stretch afferents add to this.

Why is "Inspiratory drive from the dorsal respiratory group" not the answer?

The dorsal respiratory group lies in the medulla and still drives inspiration.

Why is "Rhythm generation by the pre-Botzinger complex" not the answer?

The pre-Botzinger complex lies in the medulla and is intact after a pontine cut.

Why is "Chemoreceptor input from the carotid body" not the answer?

Carotid body input is carried by the glossopharyngeal nerve and is unaffected by this lesion.

What concept does this question test?

It tests Respiratory system: control of breathing in Physiology. Removing both leaves the apneustic centre unopposed, producing apneustic breathing with sustained inspiration. The medullary groups remain intact.

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: control 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.