BSC 2086 1st Edition Lecture 15 Outline of Last Lecture I Introduction to Lymphatic System II Major Structures III IV V Lymphocytes Lymphoid System Components Lymphatic System and Body Defenses Outline of Current Lecture I Nonspecific Defenses II Specific Defenses III Cells and Immunity IV Immunity Disorders V Effects of Aging on Immune System Current Lecture I Nonspecific Defenses a Continuation of Lymphatic System and Body Defenses b Interferons i Cytokines proteins released by activated macrophages and lymphocytes 1 Cytokines work as chemical messengers and are released by tissue cells 2 Coordinate local activities 3 Act as hormones to affect entire body ii Stimulate macrophage activity NK cells and slows inflammation c Complement i 11 special complement C proteins found in plasma 1 Form complement system and complement antibody action ii Complement activation 1 Complements will work together in cascades 2 Two pathways involved in activating the complement system a Classical pathway i Fast method ii Complement protein will bind with antibody molecule which is attached to antigen bacterium iii Bound protein will act as enzyme and catalyze chain reaction b Alternative pathway i Complement proteins interact with plasma ii Results in attachment of activated complement protein onto bacterial cell wall 3 Both paths end in a Conversion of inactive complement protein C3 to active form C3b 4 Effects a Pore formation i Destroy target plasma membranes 1 Five complement proteins will join to form membrane attack complex MAC 2 Causes cell to lyse b Enhances phagocytosis i Opsonization complement coated items attract phagocytes c Releases histamines i Comes from mast cells and basophils ii Increases local inflammation and the amount of local blood flow d Inflammation i Aka inflammatory response ii Local response iii Triggered by any stimulus that kills cells or injures tissues iv Cardinal signs quantitative measurable and symptoms qualitative you can feel them 1 Swelling tumor 2 Redness rubor 3 Heat calor 4 Pain dolor v Effects 1 Temporary repair and barrier against pathogens 2 Stops spread of pathogens into the surrounding areas 3 Mobilizing of local and specific defenses a Facilitates repairs regeneration vi Products 1 Necrosis destruction of local tissue in area of injury 2 Pus debris and necrotic tissue mixture 3 Abscess pus accumulation in an enclosed space II e Fever i Maintained body temperature above 37 C 99 F ii Pyrogens 1 Any material that causes a raise in body temperature by the hypothalamus a Circulate pathogens toxins or antibody complexes iii Endogenous pyrogens or interleukin 1 IL 1 1 Cytokine released by active macrophages 2 High temperature may stop some viruses bacteria and increase body metabolism Specific Defenses a Specific resistance immunity i Responds to specific antigens with coordinated actions of the T cells and B cells ii T cells 1 Cell mediated immunity 2 Defend against abnormal cells and pathogens within cells iii B cells 1 Antibody mediated immunity 2 Defend against antigens and pathogens within body fluids b Forms of immunity i Innate present at birth ii Adaptive found after birth iii Active antibodies will develop after exposure to antigen 1 Naturally acquired obtained from environmental exposure to pathogens 2 Artificially induced obtained through vaccines containing pathogens a Stimulates production of antibodies by immune system iv Passive antibodies transferred from a different source 1 Naturally acquired antibodies acquired from the mother 2 Artificially induced by antibody injection c Four properties of immunity i Specificity 1 Each T or B cells will only respond to a specific antigen and ignore any others 2 Several thousand different types of lymphocytes exist each with a specific antigen receptor ii Versatility 1 Body produces many types of lymphocytes a Each will fight a different type of antigen b The active lymphocyte will clone itself to fight a specific antigen iii Memory III 1 Some active lymphocytes memory cells a Stay in circulation and provide immunity against new exposure of same antigen iv Tolerance 1 Immune system will ignore normal antigens self antigens d Immune response i Two main divisions 1 Cell mediated immunity T cells 2 Antibody mediated immunity B cells Cells and Immunity a Antigen Presentation i T cells will ONLY recognize antigens that are bound to glycoproteins in plasma membranes ii Major Histocompatibility Complex MHC Proteins 1 Human leukocyte antigens HLAs will differ among individuals 2 Membrane glycoproteins bind to antigens 3 Types a Class I found in the membranes of all nucleated cells i Pick up small peptides in cell cytoplasm and carry them to surface ii T cells will ignore normal peptides iii T cells will be activated when abnormal peptides or viral proteins are present and will destroy them b Class II found in membranes of antigen presenting cells APCs i Lymphocyte phagocytic and non phagocytic cells ii Antigenic fragments 1 From the antigenic processing of pathogens a Phagocytosis and breakdown of pathogens 2 Bind to class II proteins 3 Inserted into plasma membrane to stimulate T cells iii Antigen Presenting Cells APCs 1 Responsible for activating T cells when foreign cells and proteins are present 2 Class II MHC proteins only appear on the plasma membrane when cell is processing antigen 3 Phagocytic APCs a Macrophages in connective tissues b Kupffer cells in the liver c Microglia in the CNS 4 Non phagocytic APCs a Langerhans cells in the skin b Dendritic cells in lymph nodes and spleen b Antigen Recognition i Receptors found on inactive T cells can 1 Recognize either class I or class II MCH proteins or recognize specific antigen ii Binding will occur when MHC protein is attached to the specific antigen that the T cell is in charge of detecting c CD Markers i Membrane proteins found on T cells ii Two types 1 CD8 Markers found on memory T cells cytotoxic T cells and suppressor T cells a Respond to antigens on Class I MHC proteins 2 CD4 Markers found helper T cells a Respond to antigens on Class II MHC proteins d Costimulation i T cell must be costimulated in order for it to be activated 1 Bind to either an infected cell or an APC stimulating cell at second site a This will confirm the first signal 2 Once activated the T cell doesn t require more costimulation 3 Any cell carrying target antigen will be attacked by the T cells e Activation of CD8 T cells i By exposure to antigens on class I MHC proteins ii
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