The anterior hypothalamic “thermostat” adjusts heat balance to maintain body core temperature. Heat exchange is determined by convection, conduction, evaporation, and radiation. Radiation, conduction, and convection are determined by the difference between the skin temperature and the environmental temperature. Behavioral mechanisms can assist thermoregulation. The rate of heat loss depends primarily on the surface temperature of the skin, which is in turn a function of the skin’s blood flow. The blood flow of the skin varies in response to changes in the body’s core temperature and to changes in temperature of the external environment.

Enhance Heat Loss/Diminish Heat Gain When Ambient Temperature Is Lower Than Body Temperature

Increase cutaneous blood flow

Increase sweating (even when ambient temperature is higher than body temperature)

Remove clothing

Move to cooler environment

Decrease metabolic rate

Take sprawled posture

Diminish Heat Loss/Enhance Heat Gain When Ambient Temperature Is Lower Than Body Temperature

Decrease cutaneous blood flow Piloerect

Huddle or take ball posture

Move to warmer environment

Increase activity and movement Shivering

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