Figure 1.

Central regulation of body temperature. Body temperature is regulated autonomously in the limbic system, which includes the hypothalamus. (1) The brain receives afferent signals on the state of body temperature from core (Tc) and skin (Tsk) temperatures. Tc is sensed from temperature of blood flowing to the brain and Tsk is derived from thermal sensitive nerves distribute all over the surface of the body. (2) The signals from Tsk and Tc are matched against the temperature set-point, which is about 36.8 °C in resting condition. (3) A departure from the set-point would activate a “thermostat” response through the autonomic nervous system to recalibrate body temperature back to the set-point. (4) The recalibration of body temperature may involve changes in behavior, blood flow distribution, basal metabolic rate adjustments, and the induction of sweating if heat loss is needed. (5) The temperature set-point can also fluctuate due to the influence of circadian rhythm, adaption to physical training, heat acclimatization, and pyrogens.