Endocrinology: pineal and melatonin: 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: pineal and melatonin

Sample item

Melatonin secretion rises sharply at night and is suppressed by bright light. Which pathway drives the nocturnal rise?

AHypophyseal portal veins carrying releasing hormone to the pinealBSuprachiasmatic nucleus to the superior cervical ganglion, then noradrenergic fibres to the pinealCParasympathetic fibres from the otic ganglion to the pinealDDirect optic nerve fibres terminating on pinealocytes

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

The answer and the reasoning

B. Suprachiasmatic nucleus to the superior cervical ganglion, then noradrenergic fibres to the pineal

Retinal light signals reach the suprachiasmatic nucleus, which sends signals through the spinal cord to the superior cervical ganglion. At night postganglionic sympathetic fibres release noradrenaline onto pinealocytes, increasing melatonin synthesis from serotonin. Light inhibits this pathway.

Option by option

A. Hypophyseal portal veins carrying releasing hormone to the pineal
The pineal is not regulated by portal hypophyseal vessels, which serve the anterior pituitary.
B. Suprachiasmatic nucleus to the superior cervical ganglion, then noradrenergic fibres to the pineal (correct)
Correct. The pathway relays through the sympathetic superior cervical ganglion with noradrenaline acting on pinealocytes.
C. Parasympathetic fibres from the otic ganglion to the pineal
The pineal receives sympathetic, not parasympathetic, innervation.
D. Direct optic nerve fibres terminating on pinealocytes
The optic nerve does not end on the pineal gland, as light input reaches it only indirectly.

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, Suprachiasmatic nucleus to the superior cervical ganglion, then noradrenergic fibres to the pineal. Retinal light signals reach the suprachiasmatic nucleus, which sends signals through the spinal cord to the superior cervical ganglion.

Why is "Hypophyseal portal veins carrying releasing hormone to the pineal" not the answer?

The pineal is not regulated by portal hypophyseal vessels, which serve the anterior pituitary.

Why is "Parasympathetic fibres from the otic ganglion to the pineal" not the answer?

The pineal receives sympathetic, not parasympathetic, innervation.

Why is "Direct optic nerve fibres terminating on pinealocytes" not the answer?

The optic nerve does not end on the pineal gland, as light input reaches it only indirectly.

What concept does this question test?

It tests Endocrinology: pineal and melatonin in Physiology. At night postganglionic sympathetic fibres release noradrenaline onto pinealocytes, increasing melatonin synthesis from serotonin. Light inhibits this pathway.

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 Endocrinology: pineal and melatonin?

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.