• Created by: Rosie
  • Created on: 01-06-13 15:32


Homeostasis is the natural ability of the body to maintain a constant internal environment and the ability to return the internal conditions to a "set point" when fluctuations occur.

Involves maintaining constant chemical make-up, volume, temperature ect of the blood and tissue fluid in the body. 

Homeostasis allows the internal environement to remain constant despite changes in external environment.

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  • enzymes that control the biochemical reactions of the body are sensitive to changes in pH and temperature. 
  • Water potential changes can cause distortion to cells through shrinking or bursting due to osmosis occuring along a water potential gradient
  • blood glucose levels affect water potential. they also provide glucose to cells for respiration.
  • ability to maintain constant internal environment means organism is less dependant on external environment. wider geographical range, more ability to survive. 
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Receptor - controller - effector - feedback loop - receptor - controller- effector - feedback loop.. ect

  • Set point is the desired level at which the system operates
  • Receptors monitor set point and detect deviations from it
  • controller recieves information from receptor and sends instructions to effectors
  • effectors bring about changes to return to set point
  • feedback loop informs the receptor of the changes brought about by the effector
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Processes inside body need to be constant to allow it to function. they have to resist changes from whats going on outside the body and continue to function as usual.

This is done by homeostasis, which detects changes in body and works to bring the body back to usual conditions.

Receptors detect the changes, they inform controllers. controllers decide what needs to be done about the change and send instructions to effectors. effector follows instructions to return body to usual workings. feedback loop tells the receptor that the problem has been solved. 

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