Discuss the Role of Endogenous Pacemakers and Exogenous Zeitgebers in Biological Rhythm

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Biological rhythm is a cyclic pattern of physiological changes or changes in activity in living organisms, most often synchronised with daily, monthly, or annual cyclical changes in the environment. There are three types of Biological rhythms, Circadian rhythms have a period close to twenty four hours an example of this would be sleep/wake cycle. Ultradian rhythms have a period much shorter than twenty four hours however the frequency is much hire, examples of this would be tides, stages of sleep and feeding cycles. Last but not least Infradian rhythms have a cycle of more than twenty four hours such as the hum menstrual cycle. There are two ways of generating biological rhythms. These are Exogenous Zeitgebers and Endogenous Pacemakers. Endogenous pacemakers and Exogenous Zeitgebers can manipulate the various bodily rhythms, and have particular effects on the sleep / week cycle in the circadian rhythm. Endogenous pacemakers are separate and distinct internal rhythms that affect the bodily rhythms they are also known as internal biological clocks. Examples of this would be core body temperature, sleep-wake cycle. These rhythms will be maintained even if the environmental cues have moved. Exogenous Zeitgebers are outside influences these are environmental cues these also affect how the bodily rhythms work. Examples of this would be a cockerel crows at first light a barnacles cirri will beat whenever the tide is in. The cycle of light and darkness are the fundamental Zeitgebers for the sleep/wake cycle but the endogenous peacemaker is also involved within this circadian rhythm. However it has been artificially altered in most twenty first century humans by use of electric lights. The endogenous peacemaker within the circadian rhythm is when the light enters the retina which then travels along the optic nerve to the optic chiasma. The supra chiasmatic nucleus sends
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