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SC BIOL 101 - 43, The Immune System

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OverviewPowerPoint PresentationConcept 43.1: In innate immunity, recognition and response rely on shared traits of pathogensInnate Immunity of VertebratesBarrier Defenses of Vertebrates1. Cellular Innate Defenses of Vertebrates with WBC2. Inflammatory Responses of VertebratesSlide 83. Natural Killer CellsInnate Immune System Evasion by PathogensConcept 43.2: In acquired immunity, lymphocyte receptors provide pathogen-specific recognitionAcquired ImmunitySlide 13Slide 14Lymphocyte DevelopmentSlide 16Slide 17Active and Passive ImmunizationSlide 19Immune RejectionConcept 43.4: Disruption in immune system function can elicit or exacerbate diseaseSlide 22Acquired Immune System Evasion by Pathogensa) Attack on the Immune System: HIVb) LatencySlide 26c) Antigenic VariationSlide 28Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsOverview•Barriers help an animal to defend itself from the many dangerous pathogens it may encounter •The immune system recognizes foreign bodies and responds with the production of immune cells and proteins•Two major kinds of defense have evolved: innate immunity and acquired immunity•Both invertebrates and vertebrates depend on innate immunity to fight infection•Vertebrates have an additional immune defense known as acquired immunityCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings1. Innate immunity is present before any exposure to pathogens and is effective from the time of birth•Innate immunity consists of external barriers plus internal cellular and chemical defenses•It involves nonspecific responses to pathogens and is a rapid response, found in all classes of plant and animal life.2. Acquired immunity, or adaptive immunity, develops after exposure to agents such as microbes, toxins, or other foreign substances•It involves a very specific response to pathogens and is a slow response, found in VertebratesCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsConcept 43.1: In innate immunity, recognition and response rely on shared traits of pathogens•In insects, an exoskeleton made of chitin forms the first barrier to pathogens•Innate defenses of Invertebrates are low pH, antimicrobial peptides and phagocytosis in which an enzyme lysozyme, digests microbial cell walls.•The immune system recognizes bacteria and fungi by structures on their cell walls•An immune response varies with the class of pathogen encounteredInnate Immunity of InvertebratesCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsInnate Immunity of Vertebrates•The immune system of mammals is the best understood of the vertebrates•Innate defenses include barrier defenses, low pH, phagocytosis and antimicrobial peptides, similar to defense of Invertebrates•Additional defenses unique to vertebrates are1. The Innate defenses with WBC2. Inflammatory response3. NK cellsCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsBarrier Defenses of Vertebrates•Barrier defenses include the skin and mucous membranes of the respiratory, urinary, and reproductive tracts•Mucus traps and allows for the removal of microbes•Many body fluids including saliva, mucus, and tears are hostile to microbes•The low pH of skin and the digestive system prevents growth of microbesCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings1. Cellular Innate Defenses of Vertebrates with WBC•White blood cells (leukocytes) engulf pathogens in the body•A white blood cell engulfs a microbe, then fuses with a lysozyme to destroy the microbe•Some other examples of Leukocytes that carry phagocytosis are:–Neutrophils–Eosinophils–Dendritic cells–Macrophages (produced by differentiation of Monocytes)Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings2. Inflammatory Responses of Vertebrates•Following an injury, mast cells release histamine, which promotes changes in blood vessels; this is part of the inflammatory response•These changes increase local blood supply and allow more phagocytes and antimicrobial proteins to enter tissues•Pus, a fluid rich in white blood cells, dead microbes, and cell debris, accumulates at the site of inflammationFig. 43-8-3Pathogen SplinterMacrophageMast cellChemicalsignalsCapillaryPhagocytic cellRed blood cellsFluidPhagocytosisCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings3. Natural Killer Cells•All cells in the body (except red blood cells) have a class 1 MHC protein on their surface•Cancerous or infected cells no longer express this protein; natural killer (NK) cells attack these damaged cellsCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsInnate Immune System Evasion by Pathogens•Inflammation can be either local or systemic (throughout the body)•Fever is a systemic inflammatory response triggered by pyrogens released by toxins from pathogens•Some pathogens avoid destruction by modifying their surface to prevent recognition or by resisting breakdown following phagocytosis•Tuberculosis (TB) is one such disease and kills more than a million people a yearCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsConcept 43.2: In acquired immunity, lymphocyte receptors provide pathogen-specific recognition•A type of white blood cells called lymphocytes recognize and respond to antigens, foreign molecules•Lymphocytes that mature in the thymus above the heart are called T cells, and those that mature in bone marrow are called B cells•Lymphocytes contribute to immunological memory, an enhanced response to a foreign molecule encountered previously•Cytokines (signalling molecules) are secreted by macrophages and dendritic cells to recruit and activate lymphocytesCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsAcquired Immunity•B cells and T cells have receptor proteins that can bind foreign molecules known as Antigen•Each individual lymphocyte is specialized to recognize a specific type of molecule•Acquired Immunity of 2 types-•Humoral immune Response – In HIR, B cells after recognizing an Antigen, give rise to plasma cells, which secrete proteins called antibodies or immunoglobulins (Ig)•Cell mediated Immune response- T cells bind to antigen fragments and then activate macrophages, natural killer


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