What is homeostasis mechanism?

Homeostasis is the state in which living systems maintain constant internal, physical, and chemical circumstances. 

For example, ability of warm-blooded animals to maintain their constant body temperature despite of the external environment changes.

What are the three key components of homeostasis?

1. the receptor: collect information that something in the environment has changed.
2. the control center: receive and process information from receptor
3. the effector: opposes or enhances the stimulus in response to the control center's commands.