Homeostasis
During every moment of your life, trillions of chemical reactions are taking place in your body. The enzymes that control these reactions work best within a narrow range of conditions. One of these conditions is your internal body temperature, which should remain between 98.2 ℉ and 98.8 ℉.
If it rises only a few degrees, you could easily die from overheating. At temperatures over 106℉, many enzymes stop functioning. If your internal temperature falls below 80℉, your heart may fail.
Likewise, the levels of trace minerals in your body must stay within strict limits. For instance, if calcium levels are too high, you can slip into a coma. If they are too low, your heart beat becomes irregular.
You live in a constantly changing environment. Your body must cope not only with temperature changes but also with pollution, infection, stress, and many other conditions. Every change is a challenge to your body.
