Fight-or-Flight
When we lived in more primitive societies, it was sometimes necessary to be able to run ve...
Many people do not appreciate their sweat as they should. Without sweat, humans would overheat during the slightest amount of activity or excitement. As sweat, also known as perspiration, evaporates, it pulls heat away from the body. The average person has about two-and-a-half million sweat glands that can produce up to a liter of sweat per hour in most climates. However, when people spend extended time in hot climates, their bodies learn to produce even more perspiration, as much as three liters per hour! After working out, people sometimes detect a thin, salty coating covering their bodies. This is because perspiration is composed of water, potassium, sodium, and chloride. When the water evaporates, significant quantities of sodium and chloride, the elements of salt, are left on the skin.
When we lived in more primitive societies, it was sometimes necessary to be able to run ve...
It is important to protect ourselves from the sun's strong rays. But scientists say th...
Downhill mountain bike racing is an exciting sport. Races take place on bare ski slopes in...