Immunity

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  • Immunity
    • Phagocytosis
      • NON SPECIFIC RESPONSE
      • Phagocytes attracted to pathogen by chemicals
        • Phagocytes receptors attach to chemicals
          • Lysosomes migrate towards pathogen and engulf
            • Lysosome release lysosome enzymes to hydrolyse bacterium
              • Hydrolysis product of bacterium's absorbed by phagocyte
                • Vesicle/Vacuole formed
    • Antibodies
      • 4 x polypeptide chains (quaternary)
      • Forms antigen-antibody complex
      • PREPARE antigens for destruction
        • Cause agglutination to clump together
        • 'mark' antigens
      • Monoclonal antibodies
        • Single type of antibody that's cloned
        • Used to target specific cells eg. cancer
          • Non toxic and specific = less side effects
          • Attach themselves to receptors of cancer cells, stopping the chemical signals that stimulate growth
            • DIRECT (Herceptin)
        • MAGIC BULLET
          • Cytotoxic drug that's attatched to the monoclonal antibody
          • Disadvantage: Uses mice to induce cancer and presents dangers
          • Advantage: Been used successfully to treat
          • NON DIRECT
        • How they're produced:
          • Mouse exposed to non-self material
            • Mouses B cells produce mixture of antibodies
              • Mixed with readily dividing cells eg. cancer
                • Detergent added to break cell membranes to allow to fuse
                  • Now called Hybridoma cells.  Separated under a microscope, Each cloned.
                    • Any clone producing the antibody they want is cloned
      • 2 antigen binding sites to attach to 2 antigens to clump them together
      • Disulphide bonds
    • Cell mediated immunity (T cells)
      • Phagocyte englufs pathogen
        • Places the pathogens antigens on its surface
          • Receptors of T cell are complementary to the antigens on the surface
            • Stimulates T cells to divide by mitosis
              • Memory cells
                • Enable rapid response in the future
              • Killer cells
                • protein called perforin makes holes in cell surface membrane making it freely permeable to all substances
              • Helper cells
                • Stimulates B cells to divide and T cells to produce their antibody
              • Supressor cells
                • Delays reproduction of bacteria
      • Mature in the Thymus gland
    • Humoral Immunity (B cells)
      • Macrophage engulfs pathogen
        • Presents antigens on its surface
          • Complementry   B cell antibody attaches to antigen
            • Endocytosis, B cell engulf antigens
              • T helper cell attaches to antigens on B cell and stimulates to divide
                • CLONAL SELECTION
                  • Memory cells
                  • Plasma cells
      • Mature in the bone marrow
    • Defence mechenisms
      • Specific
        • Response is slower and specific to each patogen
      • Non specific
        • Response is immediate and the same for all pathogens
    • NON SELF
      • Lymphocytes that have receptors that only fit foreign cells remain
        • All others die or are supressed
    • Vaccinations
      • Active immunity
        • Stimulating individuals own antibodies
          • Natural
            • When the bodys infected it makes its own antibodies
          • Artificial
            • Antibodies injected
      • Passive immunity
        • introduction of antibodies from outside
          • Eg. snake venom and when antibodies pass from placenta to foetus
      • Successful vaccine
        • Few side effects
        • Must be possible to vaccinate mast majority to produce herd immunity
          • Large population vaccinated to stop pathogen spreading
            • Why the may not eliminate disease
              • Some may have defective immune systems
              • May mutate frequently, pathogen no longer recognised by immune system
              • May have objections for ethical reasons

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