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The body’s defenders

The body’s defenders. Contents. Pathogens and disease Major types of defense Nonspecific or innate immunity External defenses Internal defenses Specific or acquired immunity Lymphocyte activity. Types of acquired immunity Humoral (antibody-mediated) response Cell-mediated response

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The body’s defenders

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  1. The body’s defenders

  2. Contents • Pathogens and disease • Major types of defense • Nonspecific or innate immunity • External defenses • Internal defenses • Specific or acquired immunity • Lymphocyte activity • Types of acquired immunity • Humoral (antibody-mediated) response • Cell-mediated response • Immunity to secondary infection • Active immunity • Passive immunity • Blood groups and transfusions • Immune disorders

  3. Pathogens and disease Fungi Viruses Protozoa Bacteria Large parasites

  4. INNATE (NONSPECIFIC) IMMUNITY Rapid responses to a broad range of microbes ACQUIRED (SPECIFIC) IMMUNITY Slower responses to specific microbes External defenses Internal defenses Skin Phagocytic cells Humoral response (antibodies) Mucous membranes Antimicrobial proteins Secretions Inflammatory response Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens) Natural killer cells Two major types of defenses

  5. Innate (nonspecific) immunity First line: External defenses External defenses

  6. Microbes MACROPHAGE Vacuole Lysosome containing enzymes Innate immunity Second line: Internal defenses Phagocytic cell 1 2 • Phagocytes • Attach to and ingest invading microorganisms • Initiates the inflammatory response • Macrophages – migrants or in lymph organs • Antimicrobial proteins • Complement system– lysis of invading cells, triggers inflammation • Interferons – activate macrophages, prevent cell-to-cell spread 3 4 5 6

  7. Innate immunity Second line: Internal defenses (con’t.) • Inflammatory response • Chemicals involved • Histamines • Prostaglandins • Chemokines • Pyrogens http://www.sumanasinc.com/webcontent/anisamples/dynamicillustrations/inflammatory.html

  8. Innate immunity Second line: Internal defenses (con’t.) • Natural killer (NK) cells • Patrol body • Attack virus-infected body cells and cancer cells • Apoptosis (cell death) in cells attacked • Coelomocytes in invertebrates function in nonspecific immunity

  9. Specific (acquired) immunityThird line of defense Lymphocytes • Found in blood and lymph • Types • B – cells – mature in marrow • T – cells – mature in thymus • Helper • Cytotoxic • Display specificity to antigens (antibody generator) • Have membrane-bound antigen-receptors

  10. Two types of specific immune responses • B and T cells generate clones of • short-lived activated effector cells • long-lived memory cells

  11. Antibody action

  12. Immunity– memory cells initiate a faster, more efficient response upon reinfection

  13. Active immunity • Own system develops antibodies • Develops naturally in response to infection • Develops following immunization • Long-lasting protection but may take a long time Passive immunity • Antibodies are passed from mother to fetus via the placenta • Antibodies are passed from mother to infant via breast milk (colostrum) • Antibodies may be injected into a nonimmune person • Immediate, short-term protection

  14. Blood groups and transfusions • Problems with transfusions and transplants • Antigens on RBC’s will determine a person’s blood type: A, B, AB, O blood • Another RBC antigen: Rh factor  Rh+ or Rh-

  15. 1µm Immune disorders/diseases • Allergies – hypersensitive responses to antigens called allergens • Autoimmune diseases – immune system loses tolerance for self and turns against certain molecules of the body • Immunodeficient diseases • Inborn or primary • Acquired or secondary • AIDS – HIV attacks helper T cells

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