Homeostasis

• The conditions inside your body need to be kept steady even when the external environment changes
• Your cells need the right conditions in order to function properly, including the right conditions for enzyme action
• Homeostasis

  the regulation of the conditions inside of the body to maintain a stable internal environment, in response to changes in both internal and external conditions
• There are lots of automatic control systems inside of the body that regulate your internal environment, including both nervous and hormonal communication systems, e.g. there are control systems that maintain your body temperature, your blood glucose and your water content
• All automatic control systems are made up of three main components:

  • receptors
  • coordination centre
  • effectors
• Negative feedback

  a mechanism that automatic control systems use to keep your internal environment stable
• Too high:

  • receptor detects a stimulus - level is too high
  • the coordination centre receives and processes the information, then organises a response
  • effector produces a response, which counteracts the change and restores the optimum level - the level decreases
• Too low:

  • receptor detects a stimulus - level is too low
  • the coordination centre receives and processes the information, then organises a response
  • effector produces a response, which counteracts the change and restores the optimum level - the level increases
• The effectors will carry on producing responses for as long as they're stimulated by the coordination centre, which might make the level change too much, but the receptor detects if the level becomes too different and negative feedback starts again