The Physiology of Heat Exhaustion
Heat exhaustion is so dangerous because it throws off the body’s normal cooling systems. Normally, the body regulates its temperature through two mechanisms: sweating and vasodilation.
Under normal conditions, sweating cools us by releasing moisture through the skin’s surface. As air carries the sweat away, we feel cooler.
During vasodilation, veins and capillaries expand, and blood flow to the outer layers of the skin increases. Body heat carried in the blood radiates out from these outer layers, releasing into the environment.
But during heat exhaustion, extreme weather conditions put so much stress on the body that these cooling mechanisms cannot function properly. When it’s too humid outside, the body isn’t able to release sweat as efficiently and cooling slows. Prolonged sweating then decreases the body’s ability to radiate heat through vasodilation.
The result is that the hypothalamus—the part of the brain that controls core temperature—becomes overwhelmed. The body produces more heat than it can release, and that’s when a person starts experiencing symptoms of heat exhaustion.
Heat exhaustion symptoms include:
- Profuse sweating
- Nausea or vomiting
- Muscle cramps
Mild cases of heat exhaustion can be treated at home, but severe cases require immediate medical attention.