Immune System Handout


Immune System (three stages in defense, two major divisions)

            Non-specific: general protection (Division 1)

                        1st  stage: Skin and Mucosa

                                    Skin secretions: acidic and antimicrobial


                                                Stomach: acidic, protein-digesting enzymes

                                                Vagina: acidic to kill bacteria

                                                Mucous: sticky (flypaper for bacteria)

                        2nd  Stage: Antimicrobial proteins

Interferons: damaged/infected cells release interferons to stop

 the  spread of virus.  Surrounding cells are become

resistant to virus

Compliment Proteins: Amplifies inflammatory response

                                                Punches holes in invading cell

inflammation response

            Redness: blood flowing to area

            Heat: blood flowing to area

            Swelling: fluid from blood à tissue

                        Dilute toxins

                        Deliver Oxygen and nutrients

                                    Replace damaged tissue

                        Bring clotting proteins to area

            Pain: pressure on nerves due to swelling tissue


            Histamine, Kinins, Prostaglandins

                        All cause dilation of small vessels carrying blood

            To the infected/damaged area.  This allows more blood

 to flow into the area



            Macrophages (grown up monocytes…will live to eat again)

            Neutrophils (die after phagocytosis.)

            Eosinophils (slightly phagocytic)

Fever: Chemicals called Pyrogens raise body temp & metabolism

                        Pyrogens released by macrophages & other WBC

                        Metabolism up = tissue repair rate up

                        Liver/spleen remove zinc and iron from blood

                                    Interferes with bacterial growth

          Specific: protects against particular invaders. (Division 2)

                        3rd Stage: Depends on action of lymphocytes and the antibodies they make

                                    Types of Lymphocytes:

                                                B-cells: become immunocompetent (able to do their job) in bone

 Marrow.  Make antibodies.

T-cells: become immunocompetent in the thymus.  Several

 forms.  The most important are Helper T Cells and Cytotoxic T cells

Helper T cells stimulate the production of other B and T cells, tell the B cells to build antibodies, and attract WBC to the infected area.  HIV kills helper T cells, thus stopping the production of most white blood cells.

Cytotoxic T cells are killers of other cells.  They roam the body, looking for cells that need to be killed.  The weapons used are chemicals that kill cells (i.e. cytotoxins)

                                    Humoral Immunity: depends on substances in body “humors” (fluids)

Mostly due to antibodies produced by B-lymphocyte derived cells called plasma cells.   Antibodies bind to bacteria, toxins, viruses, or cells that look like they have been invaded by viruses.  The binding of an antibody to an antigen forms a complex that starts a chemical cascade that attracts white blood cells and signals the destruction of the things the antibody has found.  Antibodies can also activate compliment proteins that will destroy bacteria.