Homeostasis (WJEC GCSE Biology): Revision Note

The Need for Regulating Internal Conditions

• Homeostasis is the regulation of conditions inside organisms to keep them relatively constant and protected from harmful effects

• Some examples of these internal conditions include:

  • Water content (of an individual cell or of the body fluids of an organism)

  • Temperature

  • pH

  • Blood pressure

  • Blood glucose concentration

• It is important for an organism to keep these internal conditions within set limits to ensure they stay healthy and to maintain optimum conditions to allow the organism to function in response to internal and external changes

• Specifically, metabolism operates only within a narrow range of temperatures and pH 

• If these limits are exceeded, the organism may die

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

• This ensures that reactions in body cells can function and therefore the organism as a whole can live