Clinical meaning
Heat stroke is a medical emergency defined by a core body temperature exceeding 40 degrees Celsius (104 degrees Fahrenheit) with associated central nervous system dysfunction (altered mental status, seizures, coma). It represents the most severe form of heat-related illness along a continuum that includes heat cramps, heat exhaustion, and heat stroke. The human body maintains core temperature within a narrow range (36.5-37.5 degrees Celsius) through a thermoregulatory system centered in the hypothalamus. The preoptic anterior hypothalamus functions as the body's thermostat, receiving input from peripheral and central thermoreceptors and coordinating heat dissipation mechanisms. When core temperature rises, the hypothalamus activates four primary cooling mechanisms: cutaneous vasodilation (redirecting blood flow from the core to the skin surface for radiative and convective heat loss), sweating (evaporative cooling, which can dissipate up to 600 kcal/hour under ideal conditions), behavioral responses (seeking shade, removing clothing), and increased respiratory rate (minor contribution through evaporative loss from the respiratory tract). Heat stroke develops when these thermoregulatory mechanisms fail or are overwhelmed, and heat production or environmental heat gain exceeds the body's capacity for heat dissipation. There...