IMMUNE SYSTEM Pathogen agents that cause disease From the Greek Pathos suffering gen origin of Two defenses of the immune system non specific similar response to all infections First line of defense A physical barrier is merely preventative Second line of defense Internal non specific defenses specific immune system Non specific physical barriers surface features like skin does not involve specific response to specific pathogen skin dry dead competition from other microbes mucous lining traps stuff cilia lungs moves material along enzymes in tears and saliva help break down pathogens Internal non specific defense white blood cells a class of blood cells critical to immune function phagocytes cell eating neutrophils eat bacteria and viruses macrophages large eater NK natural killer cells attack virus infected cells interferon viral attack stimulated release bind to un infected cells produce broad spectrum anti viral response Other familiar non specific responses inflammation localized tissue response swelling redness pain Look at slide causes vasodilation increased leakiness from capillaries increased blood flow red and swollen phagocytes come in eat bacterial and dead tissue fever continued body temp over 99F speeds up immune system too hot for pathogens Specific Resistance The real immune system antigen any foreign substance that elicits an immune response molecules on cell surfaces mold spores pollen binds typically to a protein antibody protein produced by immune system in response to antigen attaches to antigen and combats its effects can be formed many years after initial infection memory immunity a long lasting protection resulting from reaction of specific defenses to foreign pathogens Acquired immunity acquired resistance to infection Look at slide Develops one of two ways 1 Passively produced by transfer of antibodies from another source disease fighting agent is administered shot is given to you short term 2 Actively not bc of a shot entails real immune system antibodies that develop in our bodies in response to antigens results from natural or deliberate exposure occurs over a lifetime long term Innate immunity already immune to the infection Vaccine type of active immunity DEFINITION an antigen containing preparation that increases immunity to certain diseases by inducing formation of T and memory B cells artificial induction of immune response an antigen containing preparation induces formation of memory B and T cells T Cells and B Cells both start as white blood cells originate in bone marrow as lymphocyte stem cells some migrate to Thymus thus T cell some mature in Bone thus B cell B humoral or antibody mediated immunity responds to bacteria and viruses secret antibodies which mark invaders T cell mediated immunity responds to CELLS that have been attacked by bacteria viruses attack cells BOTH involve specific receptors on cell surface Antibody immune system protein that binds to a particular antigen usually just mark invaders for destruction although it can physically block antigen from working B CELL immunity Primary Immune Response antigen binds to lymphocyte that has the specific antibody this triggers production of more B cells clonal selection because more of the specific antibody is made called effector cells specific for the invading antigen these go off into lymph and blood to find invaders Slide A variety of B cells encounter an antigen anti bodies are pre made and waiting for action Antibodies on cell surface proliferate and enter the lymph and blood as free circulating antibodies primary immune response peaks at 2 weeks then fades Secondary Immune Response memory cells long lived lymphocytes formed during primary immune response Remain in lymph until activated by exposure to the same antigen that triggered its formation why after you get chicken pox you wont get it again cells wait for 2nd attack vaccines lasts decades or a lifetime T CELLS Cell mediated immunity reacts to pathogens that have already entered cells helper cells Look at slide pathogen ingested by macrophage pathogen fragments displayed antigen presenting cell helper T cell then binds to this antigen presenting cell this whole process leads to production of other immune cells Cell Division makes More activated T cells B cells Cytotoxic T cells Which binds to an infected cell Stimulates release of a substance that pokes holes in infected cell Other proteins enter cell and kill the infected cell CLICKER Which is an example of something that elicits a response from the specific immune system A Vaccine B Inflammation C Macrophage Allergies Milder response to an antigen here called allergens 1 Sensitization first exposure Initial exposure to allergen B cells make antibodies Antibodies attach to mast cell 2 Second exposure Later exposure to same allergen Allergen binds to that antibody on mast cell Mast cell produces histamine which causes symptoms END AIDS HIV HIV Human immuno deficiency virus AIDS Acquired Immune Deficiency Syndrome attacks Helper T cells this also reduces capacity of B cell immunity B cells DO make antibodies detection of these antibodies is the diagnosis used to detect AIDS