Homeostasis
Homeostasis may be defined as the maintenance of constancy in the internal environment of the organism. This is essential for maintenance of life. Without homeostatis life ceases to exist. For example, your blood cells will cease to work and will be dead unless they are bathed in a medium which closely approximates blood in its composition. Your body works in such a manner that the blood composition always remains much the same.
Maintenance of this harmony is due to homeostasis. The regulation of our body temperature is also an example of the operation of homeostasis mechanisms. When our body temperature rises beyond 37° C, the body senses the rise in temperature by special cells in the brain which function like a thermostat. The cells send nerve impulses to the sweat gland to increase sweat secretion. The evaporation of the sweat from the body surface lowers the body temperature; other nerve impulses cause dilation of the small blood vessels (capillaries) in the skin making it look flushed. The increased blood flow brings more heat to the body surface to be radiated away. Non living objects do not possess such a system.