10.2.8 Immunity

• White blood cells


  The main component of blood involved in the immune system
• Antigens


  Special proteins covering all cells (including pathogens)
• The body detects foreign antigens as 'foreign particles' and initiates an immune response

  
• The shape of the antigen is unique to the pathogen
• Self vs non-self antigens


  The body can detect when an antigen belongs to us (self) vs when it is a foreign antigen (non-self)

  
• The immune system will not attack its own cells
• Phagocytes


  • Wrap around and engulf the pathogen itself
  • Contain digestive enzymes that break down and destroy the pathogen

  
• Phagocytosis


  The process of phagocytes engulfing and destroying pathogens

  
• Non-specific immunity


  • Phagocytes will destroy ANY pathogen

  
• Lymphocytes


  Produce and release antibodies specific to a detected foreign antigen

  
• Antibodies


  Have a region with a specific shape for a particular antigen

  
• The antigen and antibody are complementary
• Specific immunity


  • A specific antibody is created for a specific antigen

  
• Active immunity


  1. Foreign antigen detected

  2. Lymphocytes multiply

  3. Lymphocytes produce and release specific antibodies

  4. Antibodies attach to antigen

  5. Antibodies cause pathogen to clump together

  6. Phagocyte destroys pathogen

  
• Memory cells


  Remember how to make the antibodies, allowing rapid antibody production on second infection

  
• Vaccines


  Contain either antigens from the pathogen or a weakened form of the pathogen

  
• Vaccines stimulate the immune response and production of antibodies and memory cells

  
• Passive immunity


  Antibodies are injected directly into the bloodstream, the body does not make antibodies itself and no memory cells are made

  
• Passive immunity is most commonly gained when antibodies cross the placenta during pregnancy or during breastfeeding