Homeostasis (AQA GCSE Biology): Revision Note

Homeostasis: Basics

• Homeostasis is:

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function

• Regulation occurs in response to internal and external changes

• Homeostasis maintains optimal conditions for enzyme action and all cell functions

• In the human body, these include control of:

  • blood glucose concentration

  • body temperature

  • water levels

Control of homeostasis

• Maintaining controlled conditions within the body is under involuntary (automatic) control

• This means it happens without conscious thought; control may be by the nervous system (e.g. the brain) or by hormones (e.g. the pancreas releasing insulin)

• No conscious control of body temperature or blood glucose level is needed

• These automatic control systems may involve nervous responses or chemical responses

• All control systems include:

  • receptors, cells which detect stimuli

  • coordination centres (such as the brain, spinal cord and pancreas) that receive and process information from receptors

  • effectors (muscles or glands) which bring about responses to restore optimum levels