The organism has to maintain its internal environment and tends to maintain a stable, constant condition. Multiple dynamic equilibrium adjustment and regulation mechanisms make homeostasis possible. All homeostatic control mechanisms have at least three interdependent components for the variable being regulated: The receptor is the sensing component that monitors and responds to changes in the environment. When the receptor senses a stimulus, it sends information to a control center, the component that sets the range at which a variable is maintained. The control center determines an appropriate response to the stimulus. In most homeostatic mechanisms the control center is the brain. The control center then sends signals to an effector which can be muscles, organs or other structures that receive signals from the control center. After receiving the signal, a change occurs to correct the deviation by either enhancing it with positive feedback or depressing it with negative feedback. Positive feedback mechanisms are designed to accelerate or enhance the output created by a stimulus that has already been activated. Negative feedback mechanism consists of reducing the output or activity of any organ or system back to its normal range of functioning.
