General physiology: dextrose infusion distribution: 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 · General physiology: dextrose infusion distribution

Sample item

A patient is given 1 litre of 5% dextrose in water over a few hours. After the glucose is metabolised, roughly how is the remaining free water distributed between body compartments?

AAll of it remains in the interstitial spaceBAbout two thirds enters cells and one third stays extracellularCAbout two thirds stays extracellular and one third enters cellsDAlmost all of it stays within the plasma volume

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

The answer and the reasoning

B. About two thirds enters cells and one third stays extracellular

Once the glucose is taken up and metabolised, what remains is essentially free water. It spreads across total body water, about two thirds in the intracellular and one third in the extracellular compartment, and only a small fraction stays in plasma. It therefore expands the intravascular volume very little.

Option by option

A. All of it remains in the interstitial space
Free water is not confined to the interstitium and equilibrates with cells.
B. About two thirds enters cells and one third stays extracellular (correct)
Correct. Free water distributes across total body water, with about two thirds in cells.
C. About two thirds stays extracellular and one third enters cells
This reverses the proportions; cells hold the larger share of total body water.
D. Almost all of it stays within the plasma volume
Free water crosses capillaries and cell membranes freely and does not stay in plasma.

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 B, About two thirds enters cells and one third stays extracellular. Once the glucose is taken up and metabolised, what remains is essentially free water.

Why is "All of it remains in the interstitial space" not the answer?

Free water is not confined to the interstitium and equilibrates with cells.

Why is "About two thirds stays extracellular and one third enters cells" not the answer?

This reverses the proportions; cells hold the larger share of total body water.

Why is "Almost all of it stays within the plasma volume" not the answer?

Free water crosses capillaries and cell membranes freely and does not stay in plasma.

What concept does this question test?

It tests General physiology: dextrose infusion distribution in Physiology. It spreads across total body water, about two thirds in the intracellular and one third in the extracellular compartment, and only a small fraction stays in plasma. It therefore expands the intravascular volume very little.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 General physiology: dextrose infusion distribution?

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.