<prompt> Circadian rhythm is regulated bySupra chiasmatic nucleusNeurohypophysisMedullaPallidohypothalamic nucleus  <response>: A Supra chiasmatic nucleus CIRCADIAN RHYTHM is a roughly-24-hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria. Circadian system 3 major components: Central oscillator or pace maker Afferent pathways which carry entraining environmental information to the oscillator Efferent pathways that communicate the rhythmicity of the oscillator to the physiology and behavior of the organism. Circadian clock in mammals is located in the suprachiasmatic nucleus SCN, a distinct group of cells located in the hypothalamus. Destruction of the SCN results in the complete absence of a regular sleepwake rhythm. SCN receives information about illumination through the eyes. 