Gastrointestinal: concentration of bile in the gallbladder: 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: concentration of bile in the gallbladder

Sample item

Hepatic bile is concentrated five- to tenfold in the gallbladder between meals while remaining isosmotic with plasma. What drives this concentration?

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

The answer and the reasoning

B. Active sodium and chloride absorption by the mucosa, with water following osmotically

The gallbladder epithelium actively absorbs sodium and chloride, and water follows osmotically, so the bile salts, bilirubin, cholesterol and lecithin that stay in the lumen become concentrated while the fluid remains isotonic. Cholecystokinin, not secretin, contracts the gallbladder after a meal.

Option by option

  • A. Reabsorption of bile salts together with water by the epithelium

    Bile salts are retained in the lumen and not absorbed there, which is why their concentration rises.

  • B. Active sodium and chloride absorption by the mucosa, with water following osmotically (correct)

    Correct. Isosmotic absorption of salt and water concentrates the bile solutes.

  • C. Active secretion of bile salts into the gallbladder lumen

    Bile salts are not secreted by the gallbladder, and they remain in the lumen.

  • D. Contraction of the gallbladder under the influence of secretin

    Secretin stimulates pancreatic bicarbonate and does not contract the gallbladder.

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 B, Active sodium and chloride absorption by the mucosa, with water following osmotically. The gallbladder epithelium actively absorbs sodium and chloride, and water follows osmotically, so the bile salts, bilirubin, cholesterol and lecithin that stay in the lumen become concentrated while the fluid remains isotonic.

Why is "Reabsorption of bile salts together with water by the epithelium" not the answer?

Bile salts are retained in the lumen and not absorbed there, which is why their concentration rises.

Why is "Active secretion of bile salts into the gallbladder lumen" not the answer?

Bile salts are not secreted by the gallbladder, and they remain in the lumen.

Why is "Contraction of the gallbladder under the influence of secretin" not the answer?

Secretin stimulates pancreatic bicarbonate and does not contract the gallbladder.

What concept does this question test?

It tests Gastrointestinal: concentration of bile in the gallbladder in Physiology. Cholecystokinin, not secretin, contracts the gallbladder after a meal.

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: concentration of bile in the gallbladder?

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.