immunity

• what triggers an immune response?

  foreign antigens
• steps of phagocytosis?


  1.phagocyte recognizes antigens on a pathogen

  2.phagocyte engulfs the pathogen

  3.pathogen held in phagocytic vacuole

  4.lysosome fuses with phagocytic vacuole and breaks down the pathogen

  5.phagocyte presents the pathogens antigens on its surface
• types of t-cells?


  t-helper , cytotoxic t-cells ,
• what cells do phagocytes activate?

  t-cells
• what do t-cells activate?

  b-cells
• types of b-cells?

  plasma and memory
• what does the cellular response include?

  t-cells and phagocytes
• what does the humoral response include?

  b-cells ,clonal selection , monoclonal antibodies
• what is the structure of an antibody?

  light chains , heavy chains, variable regions , constant regions , hinge protein and disulphide bridges
• why do vaccines not work on all pathogens?

  antigen variation , the antigens activate the immune response therefore when they change the memory cell will no longer be able to fight them
• what is active immunity?

  when your immune system makes its own antibodies
• what is passive immunity?


  when you are given antibodies from another organism
• what are monoclonal antibodies?

  a single group of genetically identical antibodies made from b-cells
• what are monoclonal antibodies used for in medicine?

  cancer cells , pregnancy tests , ELISA tests
• structure of HIV?


  attachment proteins , capsid , lipid envelope, reverse transcriptase , genetic material , DNA integrase
• how does HIV replicate?

  1.attachment proteins attach to cd4 receptors on t-helper cell

  2.capsid released into cell

  3.reverse transcriptase turns viral RNA into DNA

  4.intergrase inserts this into the human DNA

  5.viral proteins are created and assembled into new viruses
• steps of cell mediated response?


  1.helper t-cells have receptors which attach to APCs

  2.helper t-cells activate and divide by mitosis to make clones

  3.clonded cells differentiate
• steps of the humoral response?


  1.b-cells stimulated by t-helper

  2.clonal expansion + differentiation

  3.b-cells undergo mitosis make memory and plasma cells

  4. plasma cells secrete antibodies