Immune response

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  • Immune response
    • Phagocytes
      • two types
        • Neutrophils :  multilobed nucleus and made in bone marrow. short lived but released when an infection occurs
        • Macrophages: large cells made in the bone marrow. found in body organs specially in lymph nodes.
      • engulf pathogens (non specific)
        • 1)Recognises antigens on pathogen
        • 2) By endocytosis, pathogen enters phagocyte
        • 3) Pathogen is now a in a phagosome
        • 4) Lysosomes fues to phagosome and digest the bacteria
        • 5) End products are hrmless and are realeased or absorbed in the cytoplasm.
    • Antibodies: proteins that can identify and neutralise antigens
      • antigens: molecules that stimulate immune response
      • Have a specific shape complementary to the particular antigen
      • Structure
        • Four polypeptide chains held together by disulfide bridges (2 light chains, 2 heavy chains)
        • Constant region which enables antibodies to attach to phagocytes
        • Variable region which is specific to each antigen (result of amino acid sequence)
        • Hinge region which allows for movement and allow for antibody to attach to more than one antigen
      • How they work
        • Attach to antigens on a pathogen
        • Then neutralise or agglutinate.
          • Neutralise: antibodies cover the binding sites to prevent pathogen binding to host cell
          • Agglutinate: large antibodies bind many pathogens together preventing the pathogens entering host cell
      • Response
        • Primary
          • Takes longer as immune system has to build up the number of antibodies
        • Secondary
          • Antibodies must be made again but immune system quicker and so reach a higher concentrationmore rapidly
    • primary response
      • skin- acts as a barrier.
      • mucous membranes such as the nose,throat and ears)
      • vagina has high acidity(low pH)
      • tears have antibacterial qualities
    • Communicated  response
      • Pathogen is engulfed from  cells in immune system and antigens are presented on surface of cell (macrophage)
        • Selection of correct T killer cells and T helper cells (CLONAL SELECTION)
          • Reproduction by mitosis of T helper cell (CLONAL EXPANSION)
            • 1)Release of interleukins 2) Activation of B cells 3) Reproduction of B cells (CLONAL EXPANSION AND DIFFERENTIATION)
              • B memory cells ( circulate in body providing immunological memory)
              • Plasma cells (manafacture antibodies)
          • Reproduction of T killer cells (CLONAL EXPANSION)
            • Search for infected cells, when found attach to infected cells
              • Secrete toxic substances to kill the cell and pathogens it contains
  • 1)Release of interleukins 2) Activation of B cells 3) Reproduction of B cells (CLONAL EXPANSION AND DIFFERENTIATION)
    • B memory cells ( circulate in body providing immunological memory)
    • Plasma cells (manafacture antibodies)

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