Gastrointestinal: intestinal calcium absorption: 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: intestinal calcium absorption

Sample item

A child with vitamin D deficiency has rickets and low serum calcium. Which process of calcium absorption is most impaired?

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

The answer and the reasoning

D. Active, calbindin-dependent transcellular transport in the duodenum

Calcitriol induces the apical calcium channel TRPV6, the intracellular binding protein calbindin and the basolateral calcium pump, which together make up the active transcellular calcium absorption of the duodenum and upper jejunum. Without vitamin D this active pathway fails and only a small passive fraction is absorbed.

Option by option

  • A. Calcium absorption linked to sodium-glucose cotransport

    Calcium is not absorbed through sodium-glucose cotransport.

  • B. Absorption by the stomach

    The stomach does not absorb significant calcium.

  • C. Passive paracellular diffusion in the colon

    Passive paracellular absorption is not under the control of vitamin D and is a minor route.

  • D. Active, calbindin-dependent transcellular transport in the duodenum (correct)

    Correct. Calcitriol regulates the active transcellular pathway in the proximal small bowel.

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 D, Active, calbindin-dependent transcellular transport in the duodenum. Calcitriol induces the apical calcium channel TRPV6, the intracellular binding protein calbindin and the basolateral calcium pump, which together make up the active transcellular calcium absorption of the duodenum and upper jejunum.

Why is "Calcium absorption linked to sodium-glucose cotransport" not the answer?

Calcium is not absorbed through sodium-glucose cotransport.

Why is "Absorption by the stomach" not the answer?

The stomach does not absorb significant calcium.

Why is "Passive paracellular diffusion in the colon" not the answer?

Passive paracellular absorption is not under the control of vitamin D and is a minor route.

What concept does this question test?

It tests Gastrointestinal: intestinal calcium absorption in Physiology. Without vitamin D this active pathway fails and only a small passive fraction is absorbed.

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: intestinal calcium absorption?

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.