<Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (March 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (March 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> Thermoregulation in organisms runs along a spectrum from endothermy to ectothermy . Endotherms create most of their heat via metabolic processes, and are colloquially referred to as warm - blooded . When the surrounding temperatures are cold, endotherms increase metabolic heat production to keep their body temperature constant, thus making the internal body temperature of an endotherm more or less independent of the temperature of the environment . One metabolic activity, in terms of generating heat, that endotherms are able to do is that they possess a larger number of mitochondria per cell than ectotherms, enabling them to generate more heat by increasing the rate at which they metabolize fats and sugars . Ectotherms use external sources of temperature to regulate their body temperatures . They are colloquially referred to as cold - blooded despite the fact that body temperatures often stay within the same temperature ranges as warm - blooded animals . Ectotherms are the opposite of endotherms when it comes to regulating internal temperatures . In ectotherms, the internal physiological sources of heat are of negligible importance; the biggest factor that enables them to maintain adequate body temperatures is due to environmental influences . Living in areas that maintain a constant temperature throughout the year, like the tropics or the ocean, have enabled ectotherms to develop a wide range of behavioral mechanisms that enable them to respond to external temperatures, such as sun - bathing to increase body temperature, or seeking the cover of shade to lower body temperature . </P> <Ul> <Li> Vaporization: <Ul> <Li> Evaporation of sweat and other bodily fluids . </Li> </Ul> </Li> <Li> Convection: <Ul> <Li> Increasing blood flow to body surfaces to maximize heat transfer across the advective gradient . </Li> </Ul> </Li> <Li> Conduction: <Ul> <Li> Losing heat by being in contact with a colder surface . For instance: <Ul> <Li> Lying on cool ground . </Li> <Li> Staying wet in a river, lake or sea . </Li> <Li> Covering in cool mud . </Li> </Ul> </Li> <Li> </Li> </Ul> </Li> <Li> Radiation: <Ul> <Li> releasing heat by radiating it away from the body . </Li> </Ul> </Li> </Ul>

Where does heat in the body come from
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