GI physiology: oesophageal motility: 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 · GI physiology: oesophageal motility

Sample item

A 34-year-old man has dysphagia for solids and liquids, regurgitation of undigested food and weight loss. Barium swallow shows a dilated oesophagus with a smooth tapering ('bird's beak') lower end. Which neural change explains the failure of the lower oesophageal sphincter to relax?

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

The answer and the reasoning

A. Loss of inhibitory nitric oxide and VIP neurons in the myenteric plexus

Achalasia is caused by degeneration of inhibitory ganglion neurons in the oesophageal myenteric plexus that release nitric oxide and VIP. The lower oesophageal sphincter cannot relax during swallowing, and the body of the oesophagus loses peristalsis. Manometry shows incomplete sphincter relaxation, and treatment is by pneumatic dilatation, Heller myotomy or peroral endoscopic myotomy.

Option by option

  • A. Loss of inhibitory nitric oxide and VIP neurons in the myenteric plexus (correct)

    Loss of inhibitory neurons leaves the sphincter tonically contracted.

  • B. Loss of cholinergic excitatory neurons in the myenteric plexus

    Excitatory cholinergic neurons are relatively preserved, and their loss would reduce sphincter tone rather than prevent relaxation.

  • C. Degeneration of the glossopharyngeal motor nucleus

    The glossopharyngeal motor nucleus controls the pharynx and does not govern the smooth muscle of the oesophagus.

  • D. Damage to the vagal sensory fibres of the oesophagus

    Vagal sensory loss does not cause failure of sphincter relaxation.

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 A, Loss of inhibitory nitric oxide and VIP neurons in the myenteric plexus. Achalasia is caused by degeneration of inhibitory ganglion neurons in the oesophageal myenteric plexus that release nitric oxide and VIP.

Why is "Loss of cholinergic excitatory neurons in the myenteric plexus" not the answer?

Excitatory cholinergic neurons are relatively preserved, and their loss would reduce sphincter tone rather than prevent relaxation.

Why is "Degeneration of the glossopharyngeal motor nucleus" not the answer?

The glossopharyngeal motor nucleus controls the pharynx and does not govern the smooth muscle of the oesophagus.

Why is "Damage to the vagal sensory fibres of the oesophagus" not the answer?

Vagal sensory loss does not cause failure of sphincter relaxation.

What concept does this question test?

It tests GI physiology: oesophageal motility in Physiology. The lower oesophageal sphincter cannot relax during swallowing, and the body of the oesophagus loses peristalsis. Manometry shows incomplete sphincter relaxation, and treatment is by pneumatic dilatation, Heller myotomy or peroral endoscopic myotomy.

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 GI physiology: oesophageal motility?

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.