2 1 11 Gather Process And Analyse Information From Secondary

- Homeostasis involves the detection of the change in the environment and the response to that change
- The mechanism that brings about this change is called FEEDBACK
- In feedback systems, the response alters the stimulus
- In living organisms, the feedback system has 3 main parts:
o Receptors: A type of sensor that constantly monitors the internal environment
o Control Centre: Receives info from the receptors and determines the response
o Effector: Restores the set value. Keeps environments stable.
- An example of a feedback system would be the control of body temperature
- These receptors send their information to the control centre
- The temperature control centre in mammals is the hypothalamus
- The hypothalamus responds by initiating responses to increase or decrease temperature, until it goes back to the set value (which is 37ÂșC)

Temperature control responses:
Keeping Warm
Shiver to generate heat
Hair muscles erect; insulation
Increased appetite
Blood vessels constrict; less blood flow, less heat loss
Increase in metabolism

Keeping Cool
Sweating; evaporation loses heat
Blood vessels dilate; increased blood supple, more heat lost
Hair relaxes, less insulation
Decrease in metabolism
Less exercise