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Simplified control circuit of human thermoregulation. [8]The core temperature of a human is regulated and stabilized primarily by the hypothalamus, a region of the brain linking the endocrine system to the nervous system, [9] and more specifically by the anterior hypothalamic nucleus and the adjacent preoptic area regions of the hypothalamus.
Homeostasis is an almost exclusively biological term, referring to the concepts described by Bernard and Cannon, concerning the constancy of the internal environment in which the cells of the body live and survive.
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation.
Other circumstances also affect the body's temperature. The core body temperature of an individual tends to have the lowest value in the second half of the sleep cycle; the lowest point, called the nadir, is one of the primary markers for circadian rhythms. The body temperature also changes when a person is hungry, sleepy, sick, or cold.
Sufficient stress from extreme external temperature may cause injury or death if it exceeds the ability of the body to thermoregulate. Hypothermia can set in when the core temperature drops to 35 °C (95 °F). [2] Hyperthermia can set in when the core body temperature rises above 37.5–38.3 °C (99.5–100.9 °F).
Homeothermy, homothermy or homoiothermy [1] is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environment [ 2 ] (from Greek ὅμοιος homoios "similar" and θέρμη thermē "heat").
Such variation in body temperature is called poikilothermy, though the concept is not widely satisfactory and the use of the term is declining. In small aquatic creatures such as Rotifera , poikilothermy is practically absolute, but other creatures (like crabs ) have wider physiological options at their disposal, and they can move to preferred ...
Neurons from the pre-optic and hypothalamic regions of the brain that respond to small changes in temperature have also been described, providing information on core temperature. The hypothalamus is involved in thermoregulation , the thermoreceptors allowing feed-forward responses to a predicted change in core body temperature in response to ...