Which of the following nucleus controls the circadian rhythm?: (A) Supraoptic nucleus, (B) Paraventricular nucleus, (C) Suprachiasmatic nucleus, (D) Premamillary nucleus
Answer is C. Hypothalamic control of circadian rhythm: A large number of physiologic rhythms ( body temperature, sleep-wakefulness, coisol secretion among a host of others ) in the body run to a cyclic pattern that is approximately 25 hours long. These rhythms are entrained to 24 hours due to environmental signals such as light and darkness. These signals are callwd zeitgebers. The suprachiasmatic nucleus of the hypothalamus is believed to be responsible for the rhythmicity of these circadian cyclesRef: Guyton & Hall Textbook of medical physiology- a south Indian edition 2014 pg no: 812