Defence and Antigens

• What is Immunity?


  The ability of the body to fight infection and pathogens by producing antibodies or killing infected cells
• What is the Immune System?

  The system in the body responsible for maintaining homeostasis by recognising harmful from nonharmful organisms and produces an appropriate response
• What are Pathogens?


  Viruses, Bacteria or other living things that cause disease
• What are Antigens?


  • Proteins that cause an Immune Response
  • Can be proteins on surface membrane of pathogens
  • Toxins that pathogens produce that cause harm to an organism
• What are Self-Antigens?


  • Only found on the host’s own cells and don’t trigger an immune response
  • There is great genetic variability between them in individuals
  • This is why injections cause an immune response
• What are Non-Self antigens?

  • Found on cells entering the body
  • Can be displayed by cancer cells
  • May cause an immune response
• A variety in highly specific tertiary structure distinguishes one cell from another…

  Allows White Blood Cells to recognise their own cells and foreign cells
• Different parts of the Immune System?

  • Blood - White Blood Cells
  • Lymph Nodes
  • Thymus Glands - produces T Lymphocytes
  • Bone Marrow - produces B Lymphocytes
• What are the types of Defence Mechanisms?

  • Non-Specific
  • Specific
• Non-specific responses are…


  Fast and the same for all pathogens
• Specific responses are…


  Slower and specific to each pathogen
• What are the different types of Specific Response?

  • Cell Mediated Response - T Lymphocytes
  • Humoral Response - B Lymphocytes