The hypothalamic nucleus responsible for integrating circadian rhythms and acting as the 'master biological clock' is the:
- A Suprachiasmatic nucleus (SCN) ✓
- B Paraventricular nucleus
- C Arcuate nucleus
- D Dorsomedial nucleus
Correct answer: A. Suprachiasmatic nucleus (SCN)
Explanation
The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the master circadian pacemaker, receiving direct photic input via the retinohypothalamic tract. It coordinates circadian rhythms for cortisol, melatonin, body temperature, and sleep-wake cycles. The arcuate nucleus is key for appetite regulation and GnRH/GHRH secretion; the paraventricular nucleus produces CRH, TRH, oxytocin, and vasopressin.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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