How Does the Human Body Regulate Temperature? The human body normally maintains a set body temperature. How does this happen? How do we generate additional heat when our body is too cold, and how do we cool off when we are too hot? Although part of this response is voluntary, how do we really know that we are cold, and what is our brain doing involuntarily to keep temperatures constant. At times our temperature will move away from the set point, whether through environmental effects such as exposure to cold or internal processes including fever and exercise.     How is Heat Distributed Throughout the Body? Humans are homeotherms, maintaining an average core temperature of 37 +/- 0.5 degrees Celsius. Core temperature varies slightly due to environmental and metabolic factors. Exercise or fever may raise core temperature by up to three degrees, while exposure to cold may lower core temperature by a degree. Beyond these boundaries, the human is susceptible to heat stroke (elevated temperature) or hypothermia, both of which are life threatening conditions. While core temperature is tightly regulated, skin temperature varies greatly in response to metabolism and the environment. Temperature receptors in the skin (cold and hot) detect these changes, initiating compensatory mechanisms through the central nervous system.     How Does the Body Produce Heat? Energy in the form of heat is gained by two methods: production (metabolic) and acquisition (environmental). Heat production and retention are elevated by a number of factors. 1. Muscular Activity and Shivering “ the conversion of stored chemical energy results in a net increase in heat throughout the skeletal muscle, which spreads through the body. 2. Thyroxin effect on cells “ thyroid hormones increase the basal metabolic rate in cells throughout the body, resulting in thermogenesis through increased conversion of chemical energy 3. Epinephrine, Norepinephrine and Sympathetic Innervation effect on cells “ sympathetic effects include the following: