4.3.1.6 human defence systems

• What are the non-specific defence systems of the human body against pathogens?

  The skin, the nose, the trachea and bronchi and the stomach
• how does the stomach protect the body from pathogens?

  It has hydrochloric acid
• how do the lungs protect the body from pathogens?

  the trachea and bronchi are covered in a layer of mucus and the cilia line them which brush the microbes trapped in the mucus out of the lungs
• what is the second line of defence in the body against pathogens?

  the immune system
• what happens if a pathogen enters the body?

  the immune system tries to destroy the pathogen
• what are the three ways white blood cells help to defend against pathogens?

  phagocytosis, antibody production and antitoxin production
• how does phagocytosis work?

  the phagocytes surround any pathogen in blood and then engulf and digest them
• What does the first type of lymphocyte do?

  Detect antigens as foreign and produce antibodies
• what do antibodies cause?

  pathogens to stick together and make it easier for phagocytes to engulf them
• What does the other type of lymphocyte do?

  Produce toxins to neutralise the pathogen
• what is special about antibodies and antitoxins the lymphocyte produces?

  they are highly specific to the antigen on the pathogen