Homeostasis (AQA GCSE Biology): Revision Note

Homeostasis: Basics

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

Control of homeostasis

• 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

• 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 (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