Endocrinology: adrenal medulla: 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 · Endocrinology: adrenal medulla

Sample item

Why does the adrenal medulla secrete mainly adrenaline (about 80 percent) rather than noradrenaline?

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

The answer and the reasoning

A. High local cortisol delivered by the intra-adrenal portal flow induces phenylethanolamine N-methyltransferase

Venous blood from the cortex bathes the medulla in high cortisol concentrations, which induces PNMT, the enzyme that methylates noradrenaline to adrenaline. Chromaffin cells possess dopamine beta-hydroxylase, so noradrenaline is made first and then converted. Sympathetic nerve endings lack PNMT and release noradrenaline.

Option by option

  • A. High local cortisol delivered by the intra-adrenal portal flow induces phenylethanolamine N-methyltransferase (correct)

    Correct. Cortisol-induced PNMT drives the conversion of noradrenaline to adrenaline.

  • B. The medulla lacks dopamine beta-hydroxylase, so only adrenaline accumulates

    Dopamine beta-hydroxylase is present in chromaffin cells, since noradrenaline must be synthesised first.

  • C. ACTH directly converts dopamine to adrenaline in chromaffin cells

    ACTH does not directly convert dopamine to adrenaline; cortisol acts through PNMT induction.

  • D. Angiotensin II inhibits conversion of tyrosine to DOPA in the medulla

    Angiotensin II does not block tyrosine hydroxylation in the medulla.

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 A, High local cortisol delivered by the intra-adrenal portal flow induces phenylethanolamine N-methyltransferase. Venous blood from the cortex bathes the medulla in high cortisol concentrations, which induces PNMT, the enzyme that methylates noradrenaline to adrenaline.

Why is "The medulla lacks dopamine beta-hydroxylase, so only adrenaline accum…" not the answer?

Dopamine beta-hydroxylase is present in chromaffin cells, since noradrenaline must be synthesised first.

Why is "ACTH directly converts dopamine to adrenaline in chromaffin cells" not the answer?

ACTH does not directly convert dopamine to adrenaline; cortisol acts through PNMT induction.

Why is "Angiotensin II inhibits conversion of tyrosine to DOPA in the medulla" not the answer?

Angiotensin II does not block tyrosine hydroxylation in the medulla.

What concept does this question test?

It tests Endocrinology: adrenal medulla in Physiology. Chromaffin cells possess dopamine beta-hydroxylase, so noradrenaline is made first and then converted. Sympathetic nerve endings lack PNMT and release noradrenaline.

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 Endocrinology: adrenal medulla?

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.