human defence systems

• What are non-specific defence systems?

  Defences that the body has against all types of pathogens. These include, skin, nose, trachea, bronchi and stomach.
• How does the skin prevent pathogens entering?

  The skin is a waterproof layer that prevents most pathogens from entering the body. If the skin is damaged, the wound is sealed quickly by a scab forming.
• How does the nose prevent pathogens entering?

  The nose has hairs and mucus to trap airborne pathogenic microorganisms and stop them from getting further into the body.
• How do the trachea/bronchi prevent pathogens entering?


  They have sticky mucus that traps airborne pathogens, and also the cells lining these airways have cilia that waft the mucus up to the throat to be swallowed.
• How does the stomach prevent pathogens entering?

  The stomach contains hydrochloric acid (pH2) which destroys most pathogens that are ingested in food.
• What is our specific defence system?

  The immune system tries to destroy any pathogens that enter the body. Various types of white blood cells are involved.
• What exactly do white blood cells do?

  They carry out phagocytosis, as well as producing antibodies and antitoxins.
• What is phagocytosis?

  When a white blood cell engulfs a bacteria and then destroys it by digesting it using enzymes.
• What are antitoxins?

  Chemicals produced by white blood cells that neutralise the toxins produced by bacteria. The toxins are one of the reasons why we feel ill.
• What are antibodies?

  Specific shaped molecules that can bind onto a particular pathogen so that it can be destroyed.