IMMMUNITY CHAPTER 1.4

• Immunity in animals


  Internal immune system to defend themselves against micro-organisms
• Natural immunity


  Inbuilt immune system found in animals to protect themselves
• Animals, unlike plants, have an internal immune system to defend themselves against micro-organisms
• Components of the immune system

  • Skin
  • Lymph system
  • Spleen
  • Bone marrow
• Leucocytes


  White blood cells that destroy pathogens
• Types of leucocytes


  • Lymphocytes (B and T)
  • Phagocytes
• Antigens


  Foreign proteins that invade the body
• Antibodies


  Proteins produced by B-lymphocytes to destroy invaders
• Immune response


  1. B-lymphocytes detect antigens

  2. B-lymphocytes produce antibodies

  3. Antibodies attach to antigens causing them to clump together

  4. T-lymphocytes destroy them

  5. Phagocytes engulf them through phagocytosis
• Active immunity


  Body has made antibodies through direct contact with pathogens
• B-lymphocytes


  A type of white blood cell that detects antigens and produces antibodies
• Antibodies


  Proteins produced by B-lymphocytes that recognize and bind to specific antigens
• T-lymphocytes


  A type of white blood cell that can directly attack and destroy infected cells
• Phagocytes


  A type of white blood cell that can engulf and destroy foreign substances through phagocytosis
• Antigens


  Foreign substances that trigger an immune response