Pathophysiology of Temperature Regulation

Abstract

Internal body temperature (T_core) is bound to rise beyond the upper end of the tolerable range if heat production and external heat load continue to exceed heat loss. However, an intervening factor of major importance is what may be vaguely described as general physical fitness which varies between different subjects (heat-adapted vs. non-adapted, young vs. old, healthy vs. chronically ill), and can even change acutely in an individual (euhydrated vs. dehydrated). Thus the just tolerable combination of heat production and environment is subject to considerable variation, and so is the level of T_core at which pathological symptoms first occur: a supposedly fit helicopter pilot showed definite signs of developing heatstroke at 39.1 °C T_core [343], while the marathon runner of Fig. 15.5 succeeded in finishing after 160 min, despite T_core oscillating between 41.6 and 41.9 °C during the last 20 min of the race.