Slide 1Slide 2Slide 3Innate immunity in vertebratesInterferon – protein that serves as alarm signalSlide 6Inflammation – “setting on fire”The lymphatic system is important to fight infectionsLymphatic organs are a major battleground during infectionSlide 10Slide 11The adaptive immune response counters specific invadersSlide 13Lymphocytes mount a dual defenseLymphocytes mount a dual defenseSlide 16Lymphocytes mount a dual defenseSlide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Antibodies mark antigens for eliminationSlide 27Major Histocompatibility ComplexSlide 29Slide 30Cytotoxic T cells destroy infected body cellsSlide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Biology 003: Organisms in Their EnvironmentLecture #8 – Immune SystemPhoto by Sarah WolakFigure 24.1AInnate immunity (24.1–3)The response is the same whetheror not the pathogen has beenpreviously encounteredAdaptive immunity(24.4–15)Found only invertebrates; previousexposure to thepathogen enhances theimmune responseExternalbarriers (24.1)Internaldefenses (24.1–2)The lymphatic system (24.3)• Antibodies (24.8–10)• Lymphocytes (24.11–13)• Phagocytic cells• NK cells• Defensive proteins• Inflammatory response (24.2)• Skin/ exoskeleton• Acidic environment• Secretions• Mucous membranes• Hairs• CiliaINNATE IMMUNITYInnate immunity is a series of defenses that–act immediately upon infection–are the same whether or not the pathogen has been encountered before.Invertebrates rely solely on innate immunityInnate immunity in vertebratesVertebrate innate immunity includes–Barriers: skin, tracheal cilia–Interferons: proteins produced by virus-infected cells, that help to limit the cell-to-cell spread of viruses–Phagocytic (“cell eater”) cells (white blood cells)–Neutrophils (most abundant WBC in mammals)–Macrophages are large phagocytic cells–Natural killer cells: attack virus-infected cells–Complement system - a group of about 30 kinds of proteins; creates membrane attack complex in bacteriaViral nucleic acidVirusmRNADNAInterferongenesturn onInterferon stimulatescell to turn on genesfor antiviral proteinsAntiviral proteins blockviral reproductionNewvirusesInterferonmoleculesMakes interferon;is killed by the virusIs protected against the virusby interferon from cell 1Host cell 1 Host cell 234215Figure 24.1BInterferon – protein that serves as alarm signalMacrophage ingesting bacteriaNeutrophil attacking bacteriumPhagocytic White Blood CellsInflammation – “setting on fire”Tissue damage triggers the inflammatory responseTissue injury; signalingmolecules, such as histamine,are released.Dilation and increased leakiness oflocal blood vessels; phagocytesmigrate to the area.Phagocytes (macrophages andneutrophils) consume bacteria andcellular debris; the tissue heals.Blood vesselWhite blood cellSignalingmoleculesBacteriaPinSkin surfaceSwellingBlood clotPhagocytes andfluid moveinto the areaPhagocytes21 3Figure 24.2The lymphatic system is important to fight infectionsThe lymphatic system is–involved in innate and adaptive immunity–network of lymphatic vessels that collect fluid from body tissues–similar to veins, including 1-way valves–lymph is returned to the blood•lymph organs (e.g. lymph nodes, spleen, tonsils)–packed with white blood cellsLymphatic organs are a major battleground during infectionThe lymphatic system collects–microbes from body tissuesTransports microbes to lymph nodes and organs–macrophages engulf the invaders–lymphocytes (WBCs) mount an adaptive immune responseResults in “swollen glands”–filling of lymph nodes with defensive cellsThe Lymphatic SystemLymphatic organs are indicated in pinkADAPTIVE IMMUNITYOur immune system responds to foreign molecules called antigens, which elicit the adaptive immune response.–antigens are antibody generating moleculesThe adaptive immune system–is found only in vertebrates–“remembers” an invaderThe adaptive immune response counters specific invadersInfection or vaccination triggers active immunity.Vaccination (or immunization) exposes the immune system to a vaccine–a harmless variant of a microbe or–a part of a microbe.We can temporarily acquire passive immunity by receiving premade antibodies.On May 8, 1980 smallpox virus was declared eradicated!- virus is stored only in a few national health laboratoriesVaccination - Smallpox15 million infectionsLymphocytes mount a dual defenseLymphocytes–are responsible for adaptive immunity–originate from stem cells in the bone marrow–B lymphocytes or B cells continue developing in bone marrow–T lymphocytes or T cells develop further in the thymusLymphocytes mount a dual defenseB cells–participate in the humoral immune response–secrete antibodies into the blood and lymph.T cells–participate in the cell-mediated immune response1. attack cells infected with microbes2. stimulate B cells to produce antibodies.Figure 24.5ABonemarrowStem cellImmature lymphocytesViabloodAntigenreceptorsThymusT cellB cellViabloodFinal maturationof B and T cells in alymphatic organLymphnodes,spleen, andotherlymphaticorgansHumoralimmune responseCell-mediatedimmune responseTwo differentantibodymoleculesAntigen-bindingsiteAntigenmoleculeAntigenicdeterminantAntigen-binding site and antigenic determinant have complementary shapes (“lock and key”)Lymphocytes mount a dual defenseMillions of kinds of B cells and T cells–each with different antigen receptors, capable of binding one specific type of antigen–only a few B and T cells may recognize a new antigenClonal selection musters defensive forces against specific antigensWhen an antigen enters the body, it binds to only a few B and T cells in the lymphatic systembinding with the antigen activates these lymphocytesactivation initiates clonal selectionIn clonal selection, the selected lymphocyte cells–multiply into clones of short-lived effector cells, specialized for defending against the antigenAND–multiply into memory cells, which confer long-term immunityClonal selection musters defensive forces against specific antigensThe clonal selection of B cells occurs in two phases.–In the primary immune response, clonal selection produces –effector (plasma) cells and–memory cells that may confer lifelong immunity.–In the secondary immune response, memory cells are activated
View Full Document