Immune

• Innate immune system

  Bodies natural defences
• Name bodies natural barriers

  • Skin
  • Skin flora
  • Hair and mucus
  • Blood clotting
  • Inflammation
  • Stomach acid
  • Tears, saliva and mucus contains lysozyme
  • Phagocytes
• Adaptive immune system

  Produces a specific responnto each pathogen
• Name the 2 parts of the adaptive immune system

  • Humoral
  • Cell mediated
• Where do B lymphocytes mature?

  Spleen and lymph nodes
• Where are T cells activated?

  Thymus gland
• What do B lymphocytes differentiate into?

  • B plasma cells
  • B memory cells
• What do T cells differentiate into?

  • T helper cells
  • T killer cells
  • T memory cells
• B plasma cells

  Produce antibodies
• B memory cells

  Remain dormant in the blood and can divide to form more B lymphocytes if the same antigen is encountered again
• T memory cells

  Remain dormant in the blood and can divide to form more T lymphocytes if the same antigen is encountered again
• T Killer cells

  Kill pathogens
• T Helper cells

  Produce cytokines
• Describe the humoral response

  • B lymphocytes mature in the spleen and lymph nodes
  • Receptors on B lymphocytes cell membrane respond to antigens = clonal selection
  • B lymphocytes divide to form B plasma cell and B memory cells = clonal expansion
  • B memory cells remain dormant in the blood and can divide to form more B lymphocytes if the same antigen is encountered again.
  • B plasma cells release antibodies which agglutinate microbes.
• The cell mediated response activates phagocytic cells, B lymphocytes and T lymphocytes
• Antibodies are Y shaped quaternary structure proteins made of glycoprotein molecules called immnogloblins and contain disulphide bonds that bind to specific antigens on the surface of pathogens
• Each antibody can bind to 2 antigens which allows microbes to clump together (AGGLUTINATION). This makes it easier for phagocytic cells to engulf and digest them.
• Agglutination = each antibody binds to 2 antigens allowing antibodies to clump and bind together.
• Describe the cell mediated response

  • Receptors on T lymphocytes respond to antigens = clonal selection
  • T lymphocytes divide to form T Killer cells, T helper cells and T memory cells = clonal expansion
  • Cytokines stimulate: Phagocytic cells to engulf and digest pathogens B and T Lymphocytes to undergo clonal expansion (division) B lymphocytes to produce antibodies
  • Macrophages engulf the foreign antigen which becomes incorporated into the cell membrane = ANTIGEN PRESENTATION
• Macrophages engulf the foreign antigen on the first exposure during the short latent period The antigen becomes incorporated into the macrophages cell membrane = ANTIGEN PRESENTATION T helper cells detect these antigens and release cytokines Cytokines cause B plasma cells to produce antibodies which can be released for up to 3 weeks until symptoms subside
• The cell mediated response activates phagocytic cells, B lymphocytes and T lymphocytes
• Cytokines are chemicals released by T helper cells which can stimulate:

  Phagocytic cells to engulf and digest pathogens B and T Lymphocytes to undergo clonal expansion (division) B lymphocytes to produce antibodies
• Receptors on T lymphocytes respond to antigens and can divide to form: T Killer cells, T helper cells and T memory cells.
• The secondary immune response is faster as a high concentration of antibodies are produced, memory cells undergo clonal expansion, no symptoms occur