Avtor/Urednik		Rietveld, Wop J
Naslov		Biological rhythms and the interaction with extreme environments
Tip		članek
Vir		In: Hočevar A, Črepinšek Z, Kajfež-Bogataj L, editors. Biometeorology 14. Proceedings of the 14th international congress of biometeorology. Part 2. (Vol 1); 1996 Sep 1-8; Ljubljana. Ljubljana: Slovenian meteorological society,
Leto izdaje		1996
Obseg		str. 124-33
Jezik		eng
Abstrakt		Biological rhythms and especially twenty-four rhythms in many behavioral and physiological functions have long been ascribed to the envinmental day-night cycle. Various ecternal variables besides the alternating light and darkness also have 24-hour cycles such as temperature and humidity. The role of all these external cycles in generating rhythmicity has systematically been falsified in exclusion experiments. Finally it was recognized that 24-hour rhythms can be endogenous, that is, arise within organisms. Despite their endogenous nature, circadian rhythms are responsive to light and darkness. Depending on the pahse (or time of the cycle) at which light dark is presented, a circadian rhythm can to a certain extent be adveced or delayed. Such advances and delays are called phase shifts. When an animal, including man, is exposed to the natural light-dark cycle, light will advance and delay the circadian rhythm, depending on when the animal is exposed to light. Thus the overall result is that the endogenous rhythm adopts the environmental period of precisely 24 hours. In addition to light also temperature and humidity are important external variables. In an extreme hot and arid environment as the desert these variables interact with the light signal modifying the endogenous rhythmicity. This is called masking. Envitonmental variables eiher entrain or mask rhythms depending on the importance of the variable in survival. Fundamental research, mainly on animals has given us increased insight into the circadian control system, including that of human beings.
Deskriptorji		CIRCADIAN RHYTHM ENVIRONMENTAL EXPOSURE CHRONOBIOLOGY DARKNESS LIGHTING TEMPERATURE HUMIDITY