PSB 3002 Study Guide - Midterm Guide: Circadian Clock, Circadian Rhythm, Slow-Wave Sleep
Document Summary
24 hours: free running clock, with a cycle of approx. 25 hours, controls some biological functions- sleep and wakefulness: regular daily variation in the level of illumination (sunlight and darkness) keeps the clock adjusted to 24 hours, maintained by a region in the hypothalamus called the suprachiasmatic nucleus. Lesions of the scn disrupt daily patterns of wheel running, drinking, and hormonal secretion (experiments with rats: sleep/wake cycle, cycles of physical activity and body temperature, ultradian, regulation, zeitgeber: light (cid:894)ger(cid:373)a(cid:374) for (cid:862)ti(cid:373)e giver(cid:863)(cid:895, synchronizes the endogenous rhythm. Lesions of the scn abolish these patterns; sleep occurs in bouts randomly dispersed throughout both day and night: rats with scn lesions still obtain the same amount of sleep that normal animals do. Involved in the pupillary response to light: people who have become blind because of loss of these photoreceptors can still show normal circadian rhythms.
