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Chapter 43 Warm-Up. Define the following terms: Pathogen Antigen Antibody Allergen Vaccine What are lymphocytes? Where do B cells and T cells mature?. Ch. 43 Review Warm-Up. What is the difference between innate vs. adaptive immunity? Contrast the functions of B cells and T cells.
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Chapter 43 Warm-Up • Define the following terms: • Pathogen • Antigen • Antibody • Allergen • Vaccine • What are lymphocytes? Where do B cells and T cells mature?
Ch. 43 Review Warm-Up • What is the difference between innate vs. adaptive immunity? • Contrast the functions of B cells and T cells. • How are antigens recognized by immune system cells? • What are memory cells? • How does HIV affect the immune system?
Chapter 43 THE IMMUNE SYSTEM
What you must know: • Several elements of an innate immune response • The differences between B and T cells relative to their activation and actions. • How antigens are recognized by immune system cells • The differences in humoral and cell-mediated immunity • Why Helper T cells are central to immune responses
Plant Defenses • Nonspecific responses • Receptors recognize pathogen molecules and trigger defense responses • Thicken cell wall, produce antimicrobial compounds, cell death • Localize effects
Recognition of traits specific to particularpathogens, using a vastarray of receptors Recognition of traits sharedby broad ranges ofpathogens, using a smallset of receptors • • Pathogens(such as bacteria,fungi, and viruses) Figure 43.2 Barrier defenses: INNATE IMMUNITY(all animals) SkinMucous membranesSecretions Internal defenses: Phagocytic cellsNatural killer cellsAntimicrobial proteinsInflammatory response • Rapid response Humoral response: ADAPTIVE IMMUNITY(vertebrates only) Antibodies defend againstinfection in body fluids. Cell-mediated response: Cytotoxic cells defendagainst infection in body cells. • Slower response
Antimicrobial Proteins: • Interferons(inhibit viral reproduction) • Complement system (~30 proteins, membrane attack complex) • Barrier Defenses: • Skin • Mucous membranes • Lysozyme(tears, saliva, mucus) Innate Immunity (non-specific) • Natural Killer Cells: • Virus-infected and cancer cells • Inflammatory Response: • Mast cells release histamine • Blood vessels dilate, increase permeability (redness, swelling) • Deliver clotting agents, phagocytic cells • Fever • Phagocytic WBCs: • Neutrophils (engulf) • Macrophage(“big eaters”) • Eosinophils (parasites) • Dendritic cells (adaptive response)
Adaptive Response Lymphocytes (WBCs): produced by stem cells in bone marrow • T cells: mature in thymus • helper T, cytotoxic T • B cells: stay and mature in bone marrow • plasma cells antibodies
Antigen: substance that elicits lymphocyte response • Antibody (immunoglobulin – Ig): protein made by B cell that binds to antigens
Major Histocompatibility Complex (MHC) • Proteins displayed on cell surface • Responsible for tissue/organ rejection (“self” vs. “non-self”) • B and T cells bind to MHC molecule in adaptive response • Class I: all body cells (except RBCs) • Class II: displayed by immune cells; “non-self”
Antigen-presenting cell Cell-Mediated Immune Response (T Cells) Humoral Immune Response (antibodies) Helper T cell B cell Cytotoxic T cell Plasma cell tag for destruction Identify and destroy Infected cell Antibodies
Immunological Memory • Primary immune response: 1st exposure to antigen • Memory cells: • Secondary immune response: repeat exposure faster, greater response
B cells thatdiffer inantigenspecificity Figure 43.14 Antigen Antigenreceptor Antibody Plasma cells Memory cells
Immunizations/vaccines: induce immune memory to nonpathogenic microbe or toxin • Passive immunity: via antibodies in breast milk • Allergies: hypersensitive responses to harmless antigens • Autoimmune Diseases: • Lupus, rheumatoid arthritis, Type I diabetes, multiple sclerosis • HIV: infect Helper T cells • AIDS = severely weakened immune system