VIEWS: 4 PAGES: 11 POSTED ON: 8/26/2012
Defense Against Infectious Disease Review • Disease- a disruption of homeostasis • Infectious disease- caused by a pathogen • Pathogen- disease producing organism such as bacteria, viruses, fungi, protozoan • Innate immunity- non specific immunity – Skin and body secretions – Inflammation response – Phagocytes • Neutrophils • Monocytes • Macrophages (monocytes that have migrated into tissue • Eosinophils – Interferons- proteins that protect against viruses • Acquired immunity- building up an immune response to a specific pathogen • 2 types of responses: Both involve lymphocytes which circulate in blood and lymphatic system – 1. Production of antibodies, called antibody or humoral immunity. – 2. cellular, or cell mediated, immunity • Both activated by antigens: foreign proteins • Lymphatic system- • Collects tissue fluid and filters it through the lymph nodes and thymus • Lymph nodes- help filter out and concentrate pathogens. Dense with lymphocytes Antibody, aka Humoral, Immunity • Macrophages eat bacteria- antigens are presented on surface • Helper T cells bind to macrophage and is “activated.” Signals B cell lymphocyte to react and change into a plasma cell- a plasma cell makes antibodies • Antibodies mark bacteria or other cells for death • Some B cells turn into Memory B cells Cell-mediated immunity • Macrophage eats bacteria, presents antigen on cell surface. Helper T cell binds to macrophage- is “activated” • Helper T cell stimulates another type of lymphocyte- Killer T cell (aka cytotoxic T cell) • Killer T cells multiply and attack the pathogen directly- inject enzyme Perforin into bacteria or cell, which kills them. • Release cytokines- signals rest of immune system to activate Passive vs Active immunity • Passive: Mother’s milk, placental transfer or plasma infusion • Active- patient injected with a vaccine. A weakened, dead or incomplete portion of pathogen is injected, stimulating an antibody response • History: first safe vaccine 1798 by Edward Jenner HIV • Human immunodeficiency virus • Spread by direct contact of body fluids or blood • Destroys Helper T cells • It may take 8-10 years for symptoms to appear • What role do phagocytes play in defending the body against disease? • What role does a lymph node play in defending your body against microorganisms? • What is the difference between naturally acquired passive immunity and naturally acquired active immunity?
"Defense Against Infectious Disease"