Nonspecific Resistance BODY NEEDS TO FIGHT OFF BODY S LINE OF DEFENSES Pathogens Viruses bacteria fungi and other microbes that cause disease Toxins and radiation Nonliving disease agents 1 1st Line of Defense External barriers impenetrable nonspecific a Skin and mucous membranes b No memory 2 2nd Line of Defense Nonspecific defense mechanisms a WBC macrophages antimicrobial proteins NK cells inflammation fever b Happens when pathogen break through skin membrane c No memory 3 3rd Line of Defense Immune system specific adaptive a Stimulated by antigens Involves antibodies b c Defeats pathogen d Leaves the body with memory of the pathogen EXTERNAL BARRIERS Mech Surface mainly composed of keratin tough protein hard for pathogens to penetrate o Dry and poor in nutrients for microbial growth o Keratinocytes exfoliate skin surface by getting rid of dead microbes Chem Sweat and sebum o Acid mantle thin film of lactic fatty acids that inhibit bacterial growth o Antibacterial peptides Destroys bacteria viruses and fungus Dermicidin Contained in sweat Defensins from keratinocytes neutrophils macrophages Cathelicidin from keratinocytes neutrophils macrophages Chem Vitamin D Calcitrol from sunlight Mucous Membranes o Protects digestive respiratory urinary reproductive tract open to exterior vulnerable o Lysozyme Enzyme that destroys bacteria by dissolving their cell walls Areolar Tissue Contained in mucus tears saliva o Beneath epithelial skin and mucous membranes o Hyaluronic acid Sticky tissue gel makes it hard for microbes to migrate through Hyaluronidase Enzyme that breaks down gel occurs in snake venoms and bacterial toxins PHAGOCYTIC CELLS In 2nd and 3rd Line of Defense Leukocytes o Neutrophils In connective tissue to kill Phagocytosis and digestion Often dies after a single phagocytic episode Killing Zone 1 Detects bacteria lysosome degranulate their enzymes into tissue fluid 2 Enzymes catalyze a reaction called respiratory burst 3 Superoxide hydrogen peroxide and hypochlorite highly toxic form zone o Eosinophils In mucous membranes as guards Concentrated during allergies inflammation or parasitic infection Help kill tape roundworms produce superoxide hydrogen peroxide neurotoxin Promote action of basophils and mass cells Phagocytize antigen antibody complexes Secrete antihistamine enzymes breaks down chemical mediators released by other cells during inflammation o Basophils Mast cells Stimulated by eosinophils Secretes leukotrienes to attract neutrophils and eosinophils Secretes histamine increase blood flow and speed of WBC delivery to site Secretes heparin inhibits formation of blood clots that limit WBC mobility o Lymphocytes Most in blood some in stem cells T cells Cell mediated Killer attack and destroy infected body cancer transplanted cells by secreting perforins and granzymes B cells Humoral immunity Process o Immunocompetent B cell bind to antigen o B cell Internalizes displays antigen on MHC II to TH cell o TH cells secrete interleukins which activate B cell o B cell undergoes clonal selection o Differentiation of B cells into plasma cells and memory cells o Plasma cells produce and secrete antibodies Natural Killer Cells NOT a macrophage On the lookout for pathogens or diseased host cells Attack and destroy bacteria transplanted organs tissues virus and cancer cells No memory response Binds to enemy 1 Releases perforins 2 Secretes granzymes o Proteins that polymerize a ring hole in PM o Kiss of death hole allows rapid inflow of water and salts to kill target cell o Group of protein degrading enzymes o Enters pore and destroy target cell s enzymes induce apoptosis o Monocytes From blood into connective tissue Transform into macrophages Ex Dust cells microglia Kupffer cells Specialized alveolar in lungs microglia in CNS hepatic in liver Antimicrobial Protein o Interferons Proteins secreted by infected WBCs as their dying words Alert neighboring cells and protect them from becoming infected Bind to surface receptors and activate second messenger systems Synthesis of dozens of antiviral proteins that break down viral genes or prevent viral replication Activates NK cells and macrophages resistance to cancer Does NOT promote inflammation functions to only interfere with virus production in neighboring cell o Complement System 30 globulins in nonspecific resistance and adaptive immunity Synthesized by the liver Circulated in blood activated in presence of pathogens Inactive forms named with letter and number activation splits them into fragments and named with lowercase letter Pathways 1 Classical Adaptive immunity a Antibody binds to an antigen and changes its shape exposes complement binding sites antibody b C1 binds to these sites and sets off a reaction cascade c Complement fixation Cascade that attaches chains of complement proteins to 2 Alternative Nonspecific defense a C3 breaks down into C3a and C3b b C3b binds to targets like tumor cells virus bacteria and yeasts c Triggers reaction cascade C3b accelerates splitting of more C3 more C3b 3 Lectin Nonspecific defense Lectins Plasma proteins that bind to carbohydrates Lectin binds to certain sugars of microbial cell surface a b c Triggers cascade reaction for more C3b production Methods of Pathogen Destruction 1 Inflammation a C3a stimulates mast cells basophils to secrete histamine b Activates attract neutrophils and macrophages a C3b binds Ag Ab complexes to RBCs b Macrophages of liver and spleen strip off and destroy Ag Ab complexes RBCs a Bacteria viruses and pathogens digested by neutrophils and macrophages can t b Opsonization C3b coats microbial cell and serves as binding sites for phagocyte 2 Immune clearance unharmed 3 Phagocytosis internalize them attachment 4 Cytolysis a C3b splits C5 into C5a and C5b b C5a joins C3a in proinflammatory actions c C5b binds to enemy cell and attracts C6 C7 and C8 d C5b678 binds up to 17 molecules of C9 forms membrane attack complex e Complex forms a hole in target cell electrolytes leak out water leaks in Cell ruptures Fever Aka pyrexia or febrile o Abnormal elevation of body temperature o From trauma infections drug reactions brain tumors etc o Adaptive defense mechanism people recover quickly better than using aspirin medication Promotes interferon activity Elevates metabolic rate and tissue repair Inhibits production of bacteria and virus 1 Initiates exogenous not from me pyrogens Glycolipids of bacteria and virus 2 Neutrophils and macrophages attack pathogens secrete