How Things Work
This summer has been hot enough to make the devil sweat. In fact, according to a report by the National Oceanic and Atmospheric Administration, the first six months of 2012 were the warmest recorded since 1895. Through all this triple digit madness, we were reminded to drink lots of water and stay cool in order to avoid, among other heat-associated ailments, heat stroke.
Heat stroke is a serious matter in which a person’s core body temperature goes from the normal 98.6°F to 104°F. This thermal spike triggers the central nervous system to experience widespread dysfunction, with symptoms including nausea, delirium, seizures, and possible comas.
According to an article published in The New England Journal of Medicine, heat stroke is caused by exposure to high ambient temperatures or strenuous physical activity. The authors generally categorize heat stroke as a form of hyperthermia with systemic organ dysfunctions. These malfunctions stem from breakdowns in the brain where the precise control of thermoregulation is compromised.
Normally, during a period of heat stress, a region in the brain called the hypothalamus operates as the body’s thermostat, cuing the transport of warmed blood to the skin to be cooled.
Meanwhile, the body sweats to lose its excess thermal energy — about 1.7 milliliters of sweat will get rid of 1 kilocalorie of energy. The residual salt left on the skin from sweating has to be replenished within the body, which can done by ingesting salt tablets or consuming electrolyte-rich drinks.
The initial reaction to heat stress is a coordinated, short-lived, but severe inflammatory response. Various cells in the body begin to communicate and a slew of protective molecules emerge. The complicated conversation between cells and tissues is a necessary one, functioning as a visceral alarm.
The trouble starts when the cellular conversation becomes over-stimulated, leading to heat stroke. The exaggerated inflammatory response causes high volumes of blood to be redirected away from core organs. Furthermore, when the response is too strong, doctors often see symptoms associated with poor blood circulation, rampant inflammation, and overall loss of core temperature regulation.
Another biologic response to heat stress is to expel protective proteins, appropriately called heat-shock proteins (HSPs). HSPs operate to prime the body for possible future episodes of hyperthermia. They have a variety of roles in the body, but often provide stability and assist in cellular transport. The HSP family protects the cells from oxygen deprivation, inflammation, and other noxious threats that occur during heat stress and would otherwise damage tissue.
If the body cannot produce HSPs properly during heat stress — due to genetic mutation, effects of aging, or inability to acclimate to the heat — heat stroke sets in. For example, in a 1988 article published in Science, researchers discovered an increase in the mortality of cells subjected to heat stress when HSP genes were mutated to produce abnormal protein structures.
Heat stroke is a complicated malady and is contingent on multiple biological processes running amok. This illness mostly affects the elderly, infants, athletes, and outdoor laborers; however, it has been seen in every age group and is associated with numerous activities.
The best preventive action is to take time to acclimate to the heat: Drink plenty of water, eat salty foods to replenish salt lost from sweating, and conduct outdoor activities during cooler parts of the day.