cell recognition and immune system

• what can the specialised cells in the immune system detect?

  cells from other organisms, toxins, pathogens and abnormal body cells.
• antigens

  foreign signals

  • antigens are molecules that are present on the cell surface membrane of all cells
  • antigens signal to the immune system if the cell is foreign.
• antigens

  specificity

  • every cell has specific antigens
  • antigens bind to the complementary receptors on the cell surface membrane of the immune cells
  • foreign antigens will induce an immune response.
• antigens

  'self' signals

  • not all antigens induce an immune response
  • antigens can signal if cells are 'self' or they belong to the host organism
• phagocytosis

  • pathogens are ingested by specialised cells called phagocytes
  • pathogens are destroyed inside the phagocytes
• activation of T cells

  • phagocytes activate T lymphocyte cells
  • 2 types of T cells; Helper T cells and Cytotoxic T cells
  • the action at T cells is called the cellular response
• activation of B cells

  • T cells activate B lymphocyte cells
  • B cells divide into plasma cells
  • the activation of the B cells is called the humoral response
• production of antibodies

  • plasma cell will secrete antibodies
• immune response:

  1. phagocytosis
  2. activation of T cells
  3. activation of B cells
  4. production of antibodies