Homeostasis

What is homeostasis?

Homeostasis is the maintenance of a relatively stable internal environment.

Organisms are able to detect changes that could disrupt their stable internal environment.

• The change that the animal detects is called a stimulus
• The part of the organism that detects the change is called the receptor
• Information about the stimulus can be processed by a control centre (brain), which coordinates a response
• The part of the organism which causes the response is called the effector

Stimulus-Response Model 

Stimulus  ->  Receptor  ->  Control Center  ->  Effector  ->  Response

example:  Cold Temperatue -> Skin  ->  Brain->  Muscles  -> Shivering 

example:  Hot Temperature   ->  Skin  ->  Brain  ->  Sweat Glands  ->  Sweating  

Positive and Negative Feedback Loops

A negative feedback loop produces a response that is opposite to the stimulus.

A positive feedback loop produces a response that is the same as the stimulus.