How does the body cool off?
The human body cools off by utilizing its three million sweat glands. Nerves in your skin tell your brain that your body is getting hot, and the brain signals the sweat glands to get busy. Each gland is like a little pump that draws water from nearby capillaries and delivers it to the skin, cooling it off. Since up to 60 percent of the body is water, sweat glands are like wells tapping into a giant ocean. There are two types of sweat glands: eccrine glands and apocrine glands. The eccrine glands are specifically designed for cooling the body off, and can pump up to 2 quarts (1.9 liters) of water an hour during intense activity or exercise. The apocrine glands are triggered by emotional stimuli, not heat. These glands secrete sweat in the hair follicles of the armpit, groin, and nipples, where the sweat mixes with bacteria and oils, giving it color and odor. As the sweat dries up, your skin cools off, and your body temperature drops.