immune system and defences

• Non specific defences work against any type of pathogen.
• Specific defences are specific to a particular pathogen.
• 4 non specific defences:

  • skin
  • stomach acid
  • hairs and mucus
  • tears in eyes
• the skin covers the body and acts a physical barrier to pathogens and also produces oils and antimicrobial substances that kill them.
• the stomach acid that has a very low pH destroys pathogens
• Some of the cells that line the trachea and bronchi produce mucus that traps pathogens
• The immune systems main role is to locate and destroy harmful pathogens that enter the body
• 3 main function of the white blood cells:

  • Phagocytosis
  • producing antibodies
  • producing antitoxins
• Phagocytosis is the process by which phagocyte engulfs and destroys a pathogen
• Main steps of Phagocytosis:

  • Phagocyte tracks down and binds to a pathogen
  • the phagocytes membrane surround the pathogen and engulf it
  • Enzymes inside the phagocytes break down and destroy the pathogen
• An antigen is anything that your body senses as foreign, causing the immune system to produce antibodies against it. The toxins and cell walls of pathogens would be considered antigens
• An antibody is a protein produced by a white blood cell that binds to a specific antigen and destroy it.
• Antitoxins are small proteins produced by white blood cells that bind and neutralise the toxins produces by bacteria.
• antibodies bind to antigens that have a complementary shape.