Defence mechanisms help the body protect itself against the entry of microorganisms and resulting communicable diseases.

If a microorganism does enter, there are more mechanisms in place to destroy it quickly.

Preventing entry

  • Skin – a barrier to microorganisms.
  • Mucous membranes – present in the respiratory system to trap microorganisms.
  • Blood clotting – stops blood escaping and prevents the entry of microorganisms where the skin has been damaged.

The entry of a microorganism may cause us to be sick while our body fights the infection.