Vascular and sweating responses to regional heating of the body surface

¹ Department of Physiology, Stritch School of Medicine, and Graduate School of Loyola University, Chicago, Illinois

The significance of cutaneous and internal thermoreceptors in human temperature regulation was studied by exposing the subject simultaneously to environmental temperatures of 25 and 60 C. Cutaneous, rectal, and tympanic membrane temperatures were recorded along with sudomotor and vasomotor responses. Heat stress to the lower half of the body was accompanied by marked differential vasomotor responses and a pronounced caudal-to-rostral recruitment of sweating in spite of an unchanging or declining tympanic membrane temperature. Heating the upper half resulted in essentially the same vasomotor and sudomotor responses but with significant alteration in the time course and intensity of the sweat recruitment pattern. With sudden lowering of the ambient temperature, sweating on all areas disappeared while internal temperatures remained unchanged. It is clearly demonstrated that under the given experimental conditions both cutaneous and internal thermoreceptors play a significant role in human temperature regulation and that the hypothalamus is not the sole moderator of internal temperature control.