human defences

• barriers to reduce the entry of pathogens

  Hairs in the nose

  Skin
• How does skin help to defend against disease?

  It secretes oils and antimicrobials substances that kill pathogens

  It covers the body, physically preventing pathogens from entering
• Does skin act as a physical or chemical barrier to pathogens?

  physical
• What substance does the stomach produce to kill pathogens?

  hydrochloric acid
• What is the role of the immune system?

  To locate and destroy pathogens that enter the body
• functions of white blood cells

  Producing antibodies

  Phagocytosis

  produce anti toxins
• Stages of phagocytosis

  Phagocytosis is carried out by a special type of white blood cell called a phagocyte.

  The first step is for the phagocyte to track down a pathogen, and then bind to it.

  The phagocyte's membrane will then surround the pathogen and engulf it.

  Finally, enzymes inside the phagocyte break down the pathogen in order to destroy it
• What do anti-toxins do?

  Neutralise toxins released by bacteria