Physiology of Temperature Regulation

Abstract

This exhaustive review begins with a section on responses to cold dealing with metabolic responses and with body insulation and average temperature. This is followed by a consideration of responses to heat vasodilatation, insensible perspiration, sweating, and panting. The discussion of temperature regulation marshals the evidence for the parts played by receptors of skin, hypo-thalamus, and other body areas. It is assumed that the combined effects of cold and warm receptors prescribe in some as yet undetermined additive manner the action of the thermoregulator, and that the regulator has the properties of proportional and rate control, but not of integral control. Transient and long term thermal stresses, as well as those originating on the inside or outside of the body, were noted to have different actions and to affect the thermal receptors differently. Zones of regulation were differentiated into vasomotor control (neutral zone), evaporative and vasomotor control (hot zone), and control of metabolic rate (cold zone). The regulation in the cold and neutral zones appears to be largely effected by peripheral receptors, whereas regulation in the hot zone and during activity appears to be more under control of central receptors. Exact proportions for the effects of peripheral and central receptors can not be evaluated at this time. It appears that the physiologic threat of overheating is more serious than of overcooling, and the effort to protect against overheating is the major function of the physiologic thermoregulator.