In chronobiology Chronobiology is a field of science that examines periodic phenomena in living organisms and their adaptation to solar and lunar related rhythms. These cycles are known as biological rhythms. "Chrono" pertains to time and "biology" pertains to the study, or science, of life. The related terms chronomics and chronome have been, entrainment of a circadian A circadian rhythm is a roughly 24-hour cycle in the biochemical, physiological or behavioral processes of living entities, including plants, animals, fungi and cyanobacteria . The term "circadian", coined by Franz Halberg, comes from the Latin circa, "around," and diem or dies, "day", meaning literally " system is the alignment of its own period and phase to the period and phase of an external rhythm. A common example is the entrainment of endogenous Endogenous substances are those that originate from within an organism, tissue, or cell . Endogenous retrovirus are caused by ancient infections of germ cells in humans, mammals and other vertebrates. Their proviruses remain in the genome and are passed on to the next generation circadian rhythms A circadian rhythm is a roughly 24-hour cycle in the biochemical, physiological or behavioral processes of living entities, including plants, animals, fungi and cyanobacteria . The term "circadian", coined by Franz Halberg, comes from the Latin circa, "around," and diem or dies, "day", meaning literally " (which in mammals are generated by the suprachiasmatic nuclei The suprachiasmatic nucleus or nuclei , abbreviated SCN, is a tiny region on the brain's midline, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle of the hypothalamus The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland) to the daily light-dark cycle. Of the several possible cues, called zeitgeber Zeitgeber is any exogenous (external) cue that synchronizes an organism's endogenous (internal) time-keeping system (clock) to the earth's 24-hour light/dark cycle. The strongest zeitgeber, for both plants and animals, is light. Other, non-photic, zeitgebers include temperature, social interactions, pharmacological manipulation and eating/drinking (German for time-giver, synchronizer), which can contribute to entrainment, bright light is by far the most effective.
Entrainment is accomplished by altering the concentration of clock components, adjusting gene expression and protein stability.[1]
References
- ^ Toh, Kong Leong (August 2008). "Basic Science Review on Circadian Rhythm Biology and Circadian Sleep Disorders" (Review, Full Text, PDF). Annals Academy Med Singapore 37 (8): 662–8. http://www.annals.edu.sg/PDF/37VolNo8Aug2008/V37N8p662.pdf. Retrieved 2009-08-15.
References
- Pittendrigh CS (1981) Circadian systems: Entrainment. In Handbook Behavioral Neurobiology, Vol. 4. Biological Rhythms, J. Aschoff, ed. pp. 239-68, University of California Press, New-York.
Categories: Circadian rhythms
Dispersyn, Garance; Pain, Laure; Touitou, Yvan
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