Temperature regulation.

The general way of looking at short-term temperature regulation has not fundamentaly changed since 1968. Some points nevertheless have been developed and deserve special attention: 1. The influence of water on the skin surface inhibits sweat secretion (55, 106). This fact may be the explanation of sweating fatigue and of discordant conclusions regarding the functioning of the regulator, particularly during exercise in man. 2. Since a large number of studies have shown that appropriate behaviors occur in response to all the stimuli that activate autonomic responses, behavior itself should be considered as an integral part of the thermoregulatory system (1, 2, 16, 18, 19, 21, 23, 25, 31, 32, 34-36, 48, 88, 89, 98, 99, 122, 126, 127, 137). 3. The description of the peripheral input for the control of sweating with regard to mean skin temperature (104) and time dependence (159) has been improved. Among internal temperature sensors those of the spinal cord have been extensively studies (25, 27, 32, 36, 42, 59-63, 71-75, 82, 83, 86, 113-115, 121, 150, 158) and demonstrated to have a sensitivity equal to that of the hypothalamic sensors (73, 75). 4. New hypotheses have been proposed describing the overall mechanism responsible for a constant temperature in the core (58, 96, 97, 135). These stimulating theories have been discussed briefly herein. Mechanisms for the defense against heat and against cold can be dissociated completely from one another. In the same way the control of autonomic responses can be dissociated from the control of behavioral responses. This suggests that temperature regulation is brought about by multiple independent feedback loops. The overall system is well described, in the author's opinion, by the theory of the adjustable set point with proportional control (47).