General physiology: mechanism of antipyretic action: 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: mechanism of antipyretic action

Sample item

A febrile child's temperature falls after a dose of paracetamol. Which action best explains this?

AReduced prostaglandin E2 synthesis in the hypothalamus, restoring the lower set pointBNeutralisation of circulating endogenous pyrogensCBlockade of cold receptors in the skinDDirect uncoupling of oxidative phosphorylation to lower heat production

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

The answer and the reasoning

A. Reduced prostaglandin E2 synthesis in the hypothalamus, restoring the lower set point

Pyrogens such as interleukin-1 raise the set point through prostaglandin E2 acting in the hypothalamus. Paracetamol inhibits cyclooxygenase centrally, lowering prostaglandin E2, so the set point returns to normal and heat loss mechanisms are activated.

Option by option

A. Reduced prostaglandin E2 synthesis in the hypothalamus, restoring the lower set point (correct)
Correct. Lower prostaglandin E2 restores the normal set point.
B. Neutralisation of circulating endogenous pyrogens
Antipyretics do not neutralise circulating pyrogens; they act downstream on prostaglandin synthesis.
C. Blockade of cold receptors in the skin
Skin cold receptors are not the target, and blocking them would not reset the central set point.
D. Direct uncoupling of oxidative phosphorylation to lower heat production
Uncoupling would raise heat production, and paracetamol does not act this way.

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 A, Reduced prostaglandin E2 synthesis in the hypothalamus, restoring the lower set point. Pyrogens such as interleukin-1 raise the set point through prostaglandin E2 acting in the hypothalamus.

Why is "Neutralisation of circulating endogenous pyrogens" not the answer?

Antipyretics do not neutralise circulating pyrogens; they act downstream on prostaglandin synthesis.

Why is "Blockade of cold receptors in the skin" not the answer?

Skin cold receptors are not the target, and blocking them would not reset the central set point.

Why is "Direct uncoupling of oxidative phosphorylation to lower heat producti…" not the answer?

Uncoupling would raise heat production, and paracetamol does not act this way.

What concept does this question test?

It tests General physiology: mechanism of antipyretic action in Physiology. Paracetamol inhibits cyclooxygenase centrally, lowering prostaglandin E2, so the set point returns to normal and heat loss mechanisms are activated.

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 General physiology: mechanism of antipyretic action?

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.