Heat stroke
Heat stroke is a life-threatening illness in which failed temperature regulation causes severe hyperthermia and can damage the brain and other organs.
Thermoregulation: The processes by which an organism maintains its internal temperature within a functional range. Heat stroke develops when temperature-control mechanisms cannot keep body heat within a survivable range.
Exertional heat stroke: Heat stroke triggered by strenuous physical activity, often in athletes, military personnel, or workers. It is a distinct presentation in which intense exertion generates heat faster than the body can dissipate it.
Central nervous system: The brain and spinal cord, which coordinate sensation, movement, and many bodily functions. Confusion, seizures, or coma signal the brain dysfunction that distinguishes heat stroke.
1966 FIFA World Cup: The international football tournament held in England, whose final was played at Wembley Stadium. The 1966 final is often cited in accounts of exertional heat illness in elite sport.
Sweating: The release of fluid from skin glands, enabling evaporative cooling. Evaporation removes heat, but becomes less effective in humid air or when fluid loss is severe.
Classic heat stroke: Heat stroke caused by environmental heat exposure, especially during prolonged heat waves. It commonly affects people whose age, illness, or circumstances impair heat tolerance.
Rhabdomyolysis: The breakdown of skeletal muscle that releases cellular contents into the bloodstream. Severe heat and exertion can destroy muscle, adding risks such as kidney injury.
Badwater 135: An ultramarathon covering 135 miles through California's Death Valley and neighboring regions. Its extreme desert conditions illustrate the heat stress faced during prolonged endurance events.
Heat dissipation: The transfer of heat from an organism to its surroundings through radiation, convection, conduction, and evaporation. Heat stroke occurs when heat gain exceeds the body's capacity to shed heat.
Heat index: A measure combining air temperature and humidity to estimate how hot conditions feel to the human body. High humidity can make heat exposure more dangerous by limiting evaporative cooling.