immune systym

• Function of the immune system

  • Identify and destroy specific pathogens
  • Build long-lasting immunity against the pathogens in case they infect the body again
  • The first two lines of defence respond in a general way that treats all pathogens equally
• B cells


  A type of white blood cell that are produced in the bone marrow and mature there before they start circulating in your blood and lymphatic system
• Antigens


  Unique molecules on the surface of a pathogen (like a virus or bacteria) that can only bind to antibodies with a matching shape
• Antibodies


  Special proteins produced by B cells that can be attached to the surfaces of B cells or sent out into the blood, and can bind to a particular pathogen to identify and attack it
• Antibody production


  1. Antibody finds its match

  2. Triggers the B cell to clone itself

  3. New army produces millions of antibodies to fight the pathogen
• Antibody memory


  • After the pathogen is defeated, B-cells release antibodies and memory B cells in your bloodstream
  • They "remember" the pathogen, so if the same pathogen tries to infect you again, these memory cells can respond more quickly and effectively (provides immunity against pathogen)
• The third line of defence takes more time to respond to an infection than the second line of defence

  The lymphocyte has to find a specific pathogen with the specific antigen, taking more energy and time for our immune system
• In newborn babies, only the first two lines of defence are ready to fight pathogens


  The third line of defence, the adaptive immune response, develops slowly over time because it requires prior exposure to pathogens to build up immunological memory
• You can't become immune to a pathogen that has only encountered the first two lines of defence


  These initial lines of defence do not create a specific immune memory against that particular pathogen
• Vaccination


  Introducing a dead or weakened pathogen into the body to allow the immune system to identify the pathogen and develop weapons to fight it
• How vaccination works


  1. B cells with matching antibodies bind to unique markers on the surface of the pathogen

  2. After binding, the B cells produce antibodies and memory cells

  3. The antibodies and memory cells are weapons that target the pathogen, preparing the immune system to attack if the pathogen ever shows up again
• Vaccines are rigorously tested to make sure that they are both safe and effective, and are only approved for use when they have passed a series of tests agreed upon by the scientific community
• Herd immunity


  When enough people are vaccinated, the disease can't spread, protecting vulnerable people who can't be vaccinated