Homeostasis is the maintenance of a stable internal state within an organism.

-also known as steady state.

Organisms must respond and maintain homeostasis in relation to many factors.

Stimulus and Response

Organisms detect changes in their environment and respond to these changes in a variety of ways.

-May occur at the cellular or organism level.

Ex: human being struck on the knee with a hammer.

-A change in the environment is called a stimulus. Here being struck with the hammer is the stimulus.

-A response is the manner in which the organism reacts to the stimulus. The knee jerk reflex is the response.