lecture 2

lecture 2 - Chapter 24- The Adaptive Immune Response...

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Unformatted text preview: Chapter 24- The Adaptive Immune Response Immunity- ability of an organism to resist infection All cells involved in immunity originate from common stem cells in bone marrow. Immune system- protects against foreign cells and macromolecules Antigen/Immunogen- foreign cells or macromolecules that induce immune system Types of Immunity 1. Naturally acquired immunity 2. Artificially acquired immunity Naturally acquired immunity Can be classified as active or passive Naturally acquired active immunity ( comes from being sick and recovering) Host produces antibodies and T cells in response to an infection Immunity can last for years or lifetime Naturally acquired passive immunity Occurs when antibodies are passed from one host to another Youre not making the antibodies yourself, put getting them from somewhere else Ex. Antibodies pass through placenta from mother to fetus . These circulate in infants system for several months after birth. Lasts few weeks to months Artificially acquired immunity Can be classified as active or passive immunity Artificially acquired active immunity Result of vaccination Host makes antibodies that can last for years Vaccinations/Immunizations: To reduce risks, vaccines contain inactivated pathogens or their products Toxoid chemically modified exotoxin retains antigenicity but loses toxicity (so your body still reacts to it but it cant harm you) Tetanus, Diphtheria Killed bacteria cell formaldehyde, heat Cholera Inactivated virus formaldehyde Salk polio vaccine, Influenza Live cells/virus- More effective (but also more risky) Attenuated: has lost its virulence Tuberculosis, chickenpox Purified polysaccharide Meningitis Artificially acquired passive immunity Host receives antibodies (antiserum) from another host that has formed antibodies against a specific antigen. Ex. Snakebite victim receives antivenom Lasts only a few weeks Innate or Non-specific Immunity First line of defense Phagocytic leukocytes Engulf & destroy pathogens Move by ameboid motion (cytoplasmic streaming) Contain lysosomes Inclusions containing H2O2, lysozyme, proteases, phosphatases, nuclease, and lipases that destroy invader Engulfed bacterium fuses with lysosome and is destroyed. Phagocytic leukocytes 1. Neutrophils PMNs (polymorphonuclear leukocytes) Large numbers in blood or inflammation site indicate active infection 2. Macrophages and Monocytes called monocytes when circulating, differentiates into macrophage when enters tissues Antigen-presenting cells (macrophages become these) Macrophage present peptide antigens to T cells to activate a specific immune response Phagocytes recognize pathogens by coming in contact with them. Proteins on surface of phagocyte recognize specific structural component (ex. LPS) on pathogen....
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lecture 2 - Chapter 24- The Adaptive Immune Response...

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