The immune system

If a pathogen does manage to enter the body, the immune system will attempt to destroy it.

White blood cells are an important part of the immune system.

White blood cells help to defend the body through:

  • phagocytosis:
    • phagocytes surround any pathogens in the blood and engulf them
    • enzymes in the phagocyte break down the pathogen and destroy it
The process of phagocytosis - phagocytes surround pathogens in the blood and engulf them, while enzymes destroy the pathogenPhagocyte engulfing a bacterial cell
  • producing antibodies:
    • antibodies attach to the foreign body, eg a bacterium or virus
    • the phagocyte is then able to recognise the bacterium or virus as being foreign, and not one of the body's cells
    • antibodies also cause pathogens to stick together, making it easier for phagocytes to engulf them
  • producing antitoxins:
    • antitoxins neutralise the toxins produced by pathogens