homeostasis
(hoh-mee-oh-stay-sis)

The tendency of the body to seek and maintain a condition of balance or equilibrium within its internal environment, even when faced with external changes. A simple example of homeostasis is the body's ability to maintain an internal temperature around 98.6 degrees Fahrenheit, whatever the temperature outside.

1#   The ability or tendency of an organism or a cell to maintain internal equilibrium by adjusting its physiological processes.