GI physiology: absorption of glucose and rehydration: 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: absorption of glucose and rehydration

Sample item

A 2-year-old with acute watery diarrhoea from cholera is treated with oral rehydration solution containing glucose and sodium. Why does glucose improve sodium and water absorption despite the toxin?

AGlucose neutralises the cholera toxin in the lumenBGlucose inhibits the secretion of chloride through the cystic fibrosis channelCGlucose increases the activity of the sodium-potassium-chloride cotransporter in crypt cellsDSodium-glucose cotransport through SGLT1 remains intact and pulls water osmotically

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

The answer and the reasoning

D. Sodium-glucose cotransport through SGLT1 remains intact and pulls water osmotically

In cholera the toxin raises cAMP and drives chloride secretion by crypt cells, but the absorptive machinery on the villus cell brush border remains normal. SGLT1 transports one glucose with two sodium ions, and water follows through osmosis and paracellular routes. This coupling underlies the ORS, which reduces the need for intravenous fluids in most patients.

Option by option

A. Glucose neutralises the cholera toxin in the lumen
Glucose does not bind or neutralise the toxin, which acts intracellularly.
B. Glucose inhibits the secretion of chloride through the cystic fibrosis channel
Glucose has no effect on the chloride channel, which stays open under the influence of cAMP.
C. Glucose increases the activity of the sodium-potassium-chloride cotransporter in crypt cells
The NKCC1 transporter supports secretion in crypt cells and is not made more active by glucose.
D. Sodium-glucose cotransport through SGLT1 remains intact and pulls water osmotically (correct)
SGLT1 couples glucose to sodium uptake, so absorption survives in cholera.

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 D, Sodium-glucose cotransport through SGLT1 remains intact and pulls water osmotically. In cholera the toxin raises cAMP and drives chloride secretion by crypt cells, but the absorptive machinery on the villus cell brush border remains normal.

Why is "Glucose neutralises the cholera toxin in the lumen" not the answer?

Glucose does not bind or neutralise the toxin, which acts intracellularly.

Why is "Glucose inhibits the secretion of chloride through the cystic fibrosi…" not the answer?

Glucose has no effect on the chloride channel, which stays open under the influence of cAMP.

Why is "Glucose increases the activity of the sodium-potassium-chloride cotra…" not the answer?

The NKCC1 transporter supports secretion in crypt cells and is not made more active by glucose.

What concept does this question test?

It tests GI physiology: absorption of glucose and rehydration in Physiology. SGLT1 transports one glucose with two sodium ions, and water follows through osmosis and paracellular routes. This coupling underlies the ORS, which reduces the need for intravenous fluids in most patients.

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: absorption of glucose and rehydration?

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.