Gastrointestinal physiology: gastric acid: 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 · Gastrointestinal physiology: gastric acid

Sample item

Which agent stimulates gastric acid secretion by acting directly on the parietal cell through a G-protein coupled receptor that raises intracellular calcium?

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

The answer and the reasoning

C. Acetylcholine through M3 receptors

Acetylcholine through M3 receptors and gastrin through CCK-B receptors raise intracellular calcium, whereas histamine acts via H2 receptors and cyclic AMP. Somatostatin, secretin and prostaglandin E2 inhibit acid secretion.

Option by option

  • A. Secretin

    Secretin inhibits gastric acid and gastrin release.

  • B. Prostaglandin E2

    Prostaglandin E2 inhibits parietal cell secretion and protects the mucosa.

  • C. Acetylcholine through M3 receptors (correct)

    Correct. M3 activation uses the Gq pathway and calcium.

  • D. Somatostatin

    Somatostatin inhibits acid secretion.

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 C, Acetylcholine through M3 receptors. Acetylcholine through M3 receptors and gastrin through CCK-B receptors raise intracellular calcium, whereas histamine acts via H2 receptors and cyclic AMP.

Why is "Secretin" not the answer?

Secretin inhibits gastric acid and gastrin release.

Why is "Prostaglandin E2" not the answer?

Prostaglandin E2 inhibits parietal cell secretion and protects the mucosa.

Why is "Somatostatin" not the answer?

Somatostatin inhibits acid secretion.

What concept does this question test?

It tests Gastrointestinal physiology: gastric acid in Physiology. Somatostatin, secretin and prostaglandin E2 inhibit acid secretion.

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 Gastrointestinal physiology: gastric acid?

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.