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Slide 2 AP Biology 2006-2007 Fighting the Enemy Within Immune System Chapter 51 lymphocytes attacking cancer cell phagocytic leukocyte lymph system Slide 3 AP Biology Avenues of attack Points of entry digestive system respiratory system urogenital tract break in skin Routes of attack circulatory system lymph system Slide 4 AP Biology Why an immune system? Attack from outside lots of organisms want you for lunch! animals must defend themselves against unwelcome invaders viruses protists bacteria fungi we are a tasty vitamin-packed meal cells are packages of macromolecules no cell wall traded mobility for susceptibility Attack from inside defend against abnormal body cells = cancers All in a good days work! Slide 5 AP Biology Lines of defense 1st line: broad, external defense walls & moats skin & mucus membranes 2nd line: broad, internal defense patrolling soldiers leukocytes (phagocytic WBCs) 3rd line: specific, acquired immunity elite trained units lymphocytes & antibodies Barriers Non-specific patrol Immune system Slide 6 AP Biology 1st: External defense non-specific defense external barrier epithelial cells & mucus membranes skin respiratory system digestive system genito-urinary tract Lining of trachea: ciliated cells & mucus secreting cells Slide 7 AP Biology 1st: Chemical barriers on epithelium Skin & mucous membrane secretions sweat pH 3-5 tears washing action mucus traps microbes saliva anti-bacterial = lick your wounds stomach acid pH 2 anti-microbial proteins lysozyme digests bacterial cell walls Slide 8 AP Biology 2nd: Internal, broad range patrol leukocytes innate defense rapid response cells & proteins attack invaders that penetrate bodys outer barriers leukocytes phagocytic white blood cells anti-microbial proteins inflammatory response Slide 9 AP Biology Leukocytes: Phagocytic WBCs Neutrophils attracted by chemical signals released by damaged cells enter infected tissue, engulf & ingest microbes amoeba-like (fierce!) digest via lysosomes ~3 day life span Macrophages big eater bigger, long-lived phagocytes Slide 10 AP Biology Phagocytes yeast macrophage Slide 11 AP Biology Lymph system Production & transport of leukocytes Traps foreign invaders lymph node lymph vessels (intertwined amongst blood vessels) Slide 12 AP Biology Development of Red & White blood cells short-lived phagocytes 60-70% WBC develop into macrophages inflammatory response fight parasites Red blood cells Slide 13 AP Biology Inflammatory response Damage to tissue triggers local inflammatory response release histamines & prostaglandins capillaries dilate, more permeable increase blood supply delivers WBC, RBC, platelets, clotting factors lead to clot formation swelling, redness & heat of inflammation & infection Slide 14 AP Biology Inflammatory response Bacteria Blood vessel Chemical alarm signals Pin or splinter Blood clot Phagocytes swelling Reaction to tissue damage Slide 15 AP Biology Fever When a local response is not enough systemic response to infection activated macrophages release interleukin-1 triggers hypothalamus in brain to readjust body thermostat to raise body temperature higher temperature helps defense inhibits bacterial growth stimulates phagocytosis speeds up repair of tissues causes liver & spleen to store iron reducing blood iron levels bacteria need large amounts of iron to grow Slide 16 AP Biology 3rd: Acquired Immunity Specific defense lymphocytes B lymphocytes (B cells) T lymphocytes (T cells) antibodies immunoglobulins Responds to antigens specific microorganisms specific toxins abnormal body cells Slide 17 AP Biology selfforeign Antigens Proteins that serve as cellular name tags foreign antigens cause response from WBCs proteins belonging to: viruses, bacteria, protozoa, parasitic worms, fungi, toxins non-pathogens: pollen & transplanted tissue B cells & T cells respond to different antigens B cells recognize intact antigens invaders in blood & lymph T cells recognize antigen fragments invaders which have infected cells Slide 18 AP Biology Lymphocytes B cells mature in bone marrow humoral response system humors = body fluids produce antibodies T cells mature in thymus cellular response system Learn to distinguish self from non-self antigens during maturation Slide 19 AP Biology B cells Humoral response = in fluid defense against attackers circulating freely in blood & lymph Specific response produces antibodies against specific antigen tagging protein = immunogloblin millions of different B cells, each produces different antibodies, each recognizes a different antigen types of B cells plasma cells immediate production of antibodies short term release memory cells long term immunity Slide 20 AP Biology Antibodies Proteins that bind to a specific antigen multi-chain proteins produced by B cells antibodies match molecular shape of antigens immune system has antibodies to respond to millions of antigens (invaders) tagging system this is foreign! each B cell has ~100,000 antigen receptors Y Y Y Y Y Y Y Y variable binding region Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Slide 21 AP Biology How antibodies work Slide 22 AP Biology B cell immune response tested by B cells (in blood & lymph) 10 to 17 days for full response invader (foreign antigen) B cells + antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y recognition Y Y Y Y Y Y Y Y clone 1000s of clone cells Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y plasma cells release antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y memory cells reserves Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y YY Y Y captured invaders Slide 23 AP Biology 1 vs 2 response to disease Memory B cells allow a rapid, amplified response with future exposure to pathogen Slide 24 AP Biology How can we have so many antibody proteins & so few genes? Light chain Constant region Transcription of gene mRNA Chromosome of undifferentiated B cell B cell C C D J DNA of differentiated B cell Rearrangement of DNA V Translation of mRNA Antibody 40 genes for Variable region Variable region Heavy chain Variable DNA combinations: 1M different B cells 10M different T cells Slide 25 AP Biology Vaccinations Active immunity immune system exposed to harmless version of pathogen Stimulates immune system to produce antibodies to invader rapid response if future exposure Most successful against viral diseases Slide 26 AP Biology Jonas Salk Developed first vaccine against polio 1914 1995 April 12, 1955 Slide 27 AP Biology Polio epidemics 1994: Americas polio free Slide 28 AP Biology Passive immunity Maternal immunity antibodies pass from mother to baby across placenta or in breast milk critical role of breastfeeding in infant health mother is creating antibodies against pathogens baby is being exposed to Injection injection of antibodies short-term immunity Slide 29 AP Biology T cells Immune response to infected cells defense against invaders inside infected cells viruses & bacteria within infected cells, fungi, protozoa & parasitic worms defense against non-self cells cancer & transplant cells Kinds of T cells helper T cells stimulate immune system killer T cells attack infected body cells Slide 30 AP Biology How are cells tagged with antigens Glycoproteins on surface of cells have unique fingerprint major histocompatibility proteins (MHC) human leukocyte antigens (HLA) MHC proteins constantly export bits of cellular protein to cell surface snapshot of what is going on inside cell MHC proteins displaying self-antigens T cell Slide 31 AP Biology How do T cells know a cell is infected Infected cells digest some pathogens & export pieces to MHC proteins on cell surface antigen presenting cells (APC) T cell MHC proteins displaying foreign antigens invading pathogen T cell antigen receptors Slide 32 AP Biology T cell response helper T cell infected cell activated macrophage helper T cell stimulate B cells & antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y YY Y Y killer T cell activate killer T cells or interleukin 1 interleukin 2 Slide 33 AP Biology Attack of the Killer T cells Killer T cell binds to infected cell Destroys infected body cells binds to target cell secretes perforin protein punctures cell membrane of infected cell Infected cell destroyed Perforin punctures cell membrane Cell membrane Killer T cell Cell membrane Target cell Vesicle Slide 34 AP Biology Immune response pathogen invasion antigen exposure free antigens in bloodantigens on infected cells humoral responsecellular response B cellsT cells macrophages helper T cells plasma B cells memory B cells memory T cells cytotoxic T cells Y Y Y Y YY Y Y antibodies Y Y Y Slide 35 AP Biology HIV & AIDS Human Immunodeficiency Virus virus infects helper T cells helper T cells dont activate rest of immune system: T cells & B cells also destroy T cells Acquired ImmunoDeficiency Syndrome infections by opportunistic diseases death usually from other infections pneumonia or cancer Slide 36 AP Biology Immune system malfunctions Auto-immune diseases immune system attacks own molecules & cells lupus antibodies against many molecules released by normal breakdown of cells rheumatoid arthritis antibodies causing damage to cartilage & bone diabetes beta-islet cells of pancreas attacked & destroyed multiple sclerosis T cells attack myelin sheath of brain & spinal cord nerves Allergies over-reaction to environmental antigens allergens = proteins on pollen, from dust mites, in animal saliva Slide 37 AP Biology Key attributes of immune system 4 attributes that characterize the immune system as a whole specificity antigen-antibody specificity diversity react to millions of antigens memory rapid 2 response ability to distinguish self vs. non-self maturation & training process to reduce auto-immune disease Slide 38 AP Biology 2006-2007 Any Questions??