Physiologic rhythm

The above results possess therapeutic implications, as indicated by treatments of reproductive disorders by the periodic injection of the hormone GnRH. Whereas the pulsatile chronotherapy is based in that case on the physiological rhythm of GnRH secretion, it is tempting to extrapolate these results to the case of artificial ligands. For numerous such substances, the aim is currently to reach a constant level of the drug in the circulation, by means of devices such as cutaneous patches... 

Lille, E, Bumod, Y. (1983). Professional activity and physiological rhythms., 4

Circadian (circa = about, dia = day) Behavioral or physiological rhythms associated with the 24-hour cycle of the earth s rotation. 

J. S. Nicolis, M. Benrubi Inadequate Communication Between Selforganizing Systems and. Desynchronization of Physiological Rhythms, a Psychophysiological Study, General Systems,... 

Naturally Occurring Compounds. Many derivatives of iadole are found ia plants and animals where they are derived from the amino acid tryptophan. Several of these have important biological function or activity. Serotonin [50-67-9] (12) functions as a neurotransmitter and vasoconstrictor (35). Melatonin [73-31-4] (13) production is controlled daily by the circadian cycle and its physiological level iafluences, and seasonal rhythms ia humans and other species (36). Indole-3-acetic acid [87-51-4] (14) is a plant growth stimulant used ia several horticultural appHcations (37). 

The major drawback of these models, however, is their lack of a clear reference between model components and constituent parts of the biological system (e.g. structures like ion channels, transporter proteins, receptors, etc.). These models, therefore, do not permit the simulation of patho-physiological detail, such as the series of events that follows a reduction in oxygen supply to the cardiac muscle and, ultimately, causes serious disturbances in heart rhythm. 

Circadian rhythm 24-Hour cycles of behavior and physiology that are generated by endogenous biological clocks (pacemakers). 

Bland, B. H. (1986). The physiology and pharmacology of hippocampal formation theta rhythms. Prog. Neurobiol. 26, 1-54. 

Perturbation of the 5-HT system can elicit changes in a wide variety of behaviors. Furthermore, drugs that act on serotonergic neurons and their receptors are used to treat diseases such as depression, anxiety disorders and schizophrenia. Thus, 5-HT has been implicated in the regulation of many behaviors and physiological processes. The involvement of 5-HT in three areas - neuroendocrine function, circadian rhythms and feeding behavior - will be highlighted for illustrative purposes. 

Hormones circulate as signaling substances in the blood at very low concentrations (10 to between 10 mol L ). These values change periodically in rhythms that depend on the time of day, month, or year, or on physiological cycles. 

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