The body’s defenders

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

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

12. Antibody action

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

14. 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

15. 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-

16. 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