Metabolism is all of the chemical processes going on within the organisms. Metabolic rate—the rate of biochemical reactions – is raised by an raise  in temperature and  also body temperature is increases by an increase in metabolic rate. Most chemical reactions are exceedingly sensitive to temperature. In general the rate of a biochemical reactions doubles with each 10 degree rise in temperature up to about 45 degree Celsius at which point enzymes starts to denatured .birds mammals, are able to  be very active because they maintain body temperature near 40 degree Celsius. While heat increases the rate of chemical reactions it is also true that chemical reactions release heat .in the catabolism of glucose for example about 60 percent of the energy releases from glucose becomes heat , the remains stored as atp. Thus the high the metabolic rate the high the body temperature. During physical exercise for example the metabolic rate increases suddenly as does the body temperature. All organisms have some way of getting rid of body heat when it nears the lethal temperature.