Homeostasis (AQA GCSE Biology: Combined Science)

What is homeostasis in biology?

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

• Maintaining controlled conditions within the body is under involuntary (automatic) control
• This means that the brain stem (or non-conscious part of the brain) and the spinal cord are involved in maintaining homeostasis – you don’t consciously maintain your body temperature or blood glucose level
• These automatic control systems may involve nervous responses or chemical responses
• All control systems include:
  • Cells called receptors, which detect stimuli (changes in the environment)
  • 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 which restore optimum levels