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Circadian rhythms have been documented for centuries. For example, French astronomer Jean-Jacques d’Ortous de Mairan noted the periodic 24-hour movement of Mimosa plant leaves as early as 1729. However, science has only recently begun to uncover the cellular mechanisms responsible for driving observed circadian rhythms.
A circadian rhythm (/ s ər ˈ k eɪ d i ə n /), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours.Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrained by the environment).
In most vertebrates, exposure to light sets off a chain reaction of enzymatic events within the pineal gland that regulates circadian rhythms. [64] In humans and other mammals, the light signals necessary to set circadian rhythms are sent from the eye through the retinohypothalamic system to the suprachiasmatic nuclei (SCN) and the pineal gland.
A circadian clock, or circadian oscillator, also known as one’s internal alarm clock is a biochemical oscillator that cycles with a stable phase and is synchronized with solar time. Such a clock's in vivo period is necessarily almost exactly 24 hours (the earth's current solar day). In most living organisms, internally synchronized circadian ...
Any biological process in the body that repeats itself over a period of approximately 24 hours and maintains this rhythm in the absence of external stimuli is considered a circadian rhythm. [4] It is believed that the brain's suprachiasmatic nucleus (SCN), or internal pacemaker, is responsible for regulating the body's biological rhythms ...
The hypothalamus in the diencephalon, is involved in regulating many functions of the body. Functions include neuroendocrine regulation, regulation of the circadian rhythm, control of the autonomic nervous system, and the regulation of fluid, and food intake. The circadian rhythm is controlled by two main cell groups in the hypothalamus.
The dorsomedial hypothalamic nucleus is a nucleus of the hypothalamus.It is involved in feeding, drinking, body-weight regulation and circadian activity. [1] More specifically, it is a necessary component for the expression of numerous behavioral and physiological circadian rhythms.
The sound of each individual's voice is thought to be entirely unique [13] not only because of the actual shape and size of an individual's vocal cords but also due to the size and shape of the rest of that person's body, especially the vocal tract, and the manner in which the speech sounds are habitually formed and articulated. (It is this ...