The immune system

• What does the immune system do?

  Protects the body against pathogens
• What are physical barriers that the body has to protect against pathogens?

  Skin, Nose, Mouth, stomach
• How is the skin a barrier of pathogens?

  Secrtetes oils and antimicrobial substances which kill pathogens
• How does your nose act as a barrier against pathogens?

  Has lots of little hairs and mucus inside to trap pathogens
• How does the mouth act as a barrier against pathogens?

  Trachea is covered in a layer of mucus which traps pathogens and causes us to swallow them into our stomach
• How is the stomach a barrier against pathogens?

  Contains hydrocloric acid which is a strong acid which will kill pathogens
• What type of cells does the immune system contain that helps fight of pathogens?

  White blood cells
• What do white blood cells do?


  Patrol the body for pathogens around the blood and tissues
• What are the 3 functions of white blood cells?

  Phagocytosis, production of anti toxins, production of antibodies
• What happens in phagocytosis?

  The white blood cells consume and engulf the pathogens
• What are the steps in phagocytosis?

  Track the pathogen, Bind to the pathogen and englulf them
• What does the anti toxins do?

  They bind and counteract the toxins produces by the pathogens so they cant do damage to our cells
• What do the anitibodies do?

  They are small proteins that lock onto antigens and send signals to the white blood cells to say that they do not recognise them and they should be destroyed
• What is an antigen?


  Substances that the white blood cells see as foreign. EG, cell wall of bacteria
• What does it mean when someone is immune to disease?

  The antibodies have specific antigens that they target so when it appares one the antibodies multiply fast so if this antigen is seen again it will be destroyed almost straight away so therefore this person is immune to this disease as they are never going to catch it again