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ch 24 lecture 2

ch 24 lecture 2 - B IOL 2051 Chapter 24 Notes Chapter 24...

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BIOL 2051 Stewart Humble Chapter 24 Notes November 19, 2009 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 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 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 Tetanus, Diphtheria Killed bacteria cell – formaldehyde, heat Cholera Inactivated virus – formaldehyde Salk polio vaccine, Influenza Live cells/virus More effective Attenuated: has lost its virulence Tuberculosis, chickenpox Purified polysaccharide Meningitis
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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 Contain lysosomes Inclusions containing H 2 O 2 , 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
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