Annotation
Chronobiology studies time regulation of biological processes. Living organisms exhibit biological rhythms in many variables, from gene expression to behavior. These rhythms may run with a period from several milliseconds to many years. The most important are circadian, i.e. about one day, rhythms, which persist even in a non-periodic environment. Circadian rhythms can be found in most of the organisms known so far, from unicellular prokaryotic to mammals, including humans. It has been revealed that nearly every cell of a multicellular organism is able to generate circadian rhythms that are coordinated via so called circadian system. Malfunction of the coordination in the timekeeping system impacts negatively on many physiological functions and health.
Lectures will concentrate mostly on the mammalian circadian system and its hierarchy in different species, mainly in mammals. The up-to-day theories on mechanisms underlying the circadian rhythmicity at the cellular and molecular level will be explained. It will also be summarized how does the timekeeping mechanism entrain with external cues and how does it drive numeral physiological functions. The ontogenetic and phylogenetic aspects of the circadian rhythmicity will be also ascertained. Further, attention will be directed at relationship between circadian rhythms and rhythms with much longer or shorter period. Last but not least, circadian control of behavior of different species (migration) or regulation of sleep, learning ability etc. in humans will be discussed.