Biology · Chemical Coordination and Integration · NEET
The pineal gland is located on the dorsal (top) side of the forebrain. NEET often confuses students by naming other brain parts. Remember: pineal = dorsal forebrain. Do not mix it up with the pituitary, which hangs below the hypothalamus at the base of the brain.
The pineal gland secretes only ONE hormone: melatonin. It does not make any other hormone. This is a common one-line NEET fact, so lock it in: Pineal -> Melatonin.
Melatonin controls the 24-hour (diurnal) rhythm of the body. Its main jobs from NCERT are: (1) sleep-wake cycle, (2) body temperature. It also influences metabolism, pigmentation, the menstrual cycle, and our defence (immune) capability. But the sleep-wake cycle is the answer NEET wants most often.
Melatonin secretion is light-dependent. Melatonin normally rises in the dark and falls in light. Artificial light, extended work hours, and reduced sleep disturb this light signal, so melatonin release becomes irregular. This directly disrupts the pineal gland's activity. This exact idea was asked in NEET 2019.
No. Metabolism (basal metabolic rate) is controlled by thyroid hormones (T3 and T4), not melatonin. Melatonin's headline role is the sleep-wake rhythm. NEET 2023 used this trap: the sleep-wake cycle is NOT under thyroid control, it is under melatonin (pineal) control.
The pineal gland is a permanent endocrine gland. Do not confuse it with the corpus luteum, which is a temporary endocrine gland (it degenerates). NEET 2017 listed pineal gland as a distractor for the 'temporary endocrine gland' question, and the answer was corpus luteum, not pineal.
Artificial light, extended work-time and reduced sleep-time disrupt the activity of
Which of the following are NOT under the control of thyroid hormone? A. Maintenance of water and electrolyte balance B. Regulation of basal metabolic rate C. Normal rhythm of sleep-wake cycle D. Development of immune system E. Support the process of R.B.Cs formation
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The pineal gland secretes melatonin, which controls the 24-hour (diurnal) rhythm of the body, mainly the sleep-wake cycle and body temperature. It also influences metabolism, pigmentation, the menstrual cycle and defence capability.
Only melatonin. The pineal gland is a single-hormone gland, which makes it an easy one-mark NEET fact.
On the dorsal (top) side of the forebrain.
Melatonin rises in the dark and falls in light. Its secretion is light-dependent, which is why irregular light and sleep disturb the pineal gland.
Yes. It is a true, permanent endocrine gland that releases melatonin directly into the blood. It is different from the temporary corpus luteum.
