PSC 101 Lecture Notes - Lecture 12: Bromodeoxyuridine, Adrenalectomy, Shift Work
Document Summary
Psc 101 lecture 12 biological rhythms. Help organisms coordinate internal functions with the external environment allows an individual to anticipate predictable changes in the environment. Display a cycle of about 24 hours. Circadian rhythms are generated by internal and external cues. External cues (zeitgeber) are used by an individual to synchronize with the environment. Internal biological clocks can maintain a circadian rhythm in the absence of a zeitgeber this internal rhythm can be observed by removing zeitgebers constant darkness or dim light. Hamsters housed in constant light conditions show rhythms in activity that is slightly longer than 24 hours free-running: a rhythm not synchronized with the environment. Internal biological clocks have been studied at multiple levels hormonal, neurobiological, molecular. The suprachiasmatic nucleus of the hypothalamus is a crucial region of the brain controlling endogenous rhythms. Scn neurons show high rates of activity during the light phase true for both nocturnal and diurnal species, can be measured with 2-deoxyglucose and autoradiography.
