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Unformatted text preview: 1 The Immune System The Immune System Body Defenses & Immunity Body Defenses & Immunity s Immunity = an individual's power to resist or overcome the effects of a particular pathogen or its toxic products s Resistance = the ability to ward off disease s Susceptibility = lack of resistance Body Defenses & Immunity Body Defenses & Immunity Our body s Can distinguish between "self" & "non-self" s Able to remember previous infections & react accordingly (i.e. sensitized) s Displays both enormous diversity & extraordinary specificity Types of Immunity Types of Immunity s Non-specific immunity = physical/mechanical & chemical barriers, cellular defenses, inflammation, fever, and molecular defenses (e.g. interferon) s Specific immunity = acts against specific pathogens Types of Immunity Types of Immunity Factors Influencing Infection Factors Influencing Infection s Portal of entry s Type of tissue infected s Virulence = the power of an organism to overcome the host’s defenses, depends on its 1. invasive power 2. ability to produce toxins s # of invading pathogens s high #s of low virulence can still cause infection s Host predisposition 2 Non Non-Specific Defenses: Specific Defenses: First Line of Defense First Line of Defense Mechanical & Chemical Barriers s Intact skin s Mucous membranes lining passageways s sticky secretions, hair, cilia s Body secretions s tears, perspiration, saliva, digestive juices s Body reflexes s sneezing, coughing, vomiting, diarrhea Non Non-Specific Defenses: Specific Defenses: 2 nd nd Line of Defense Line of Defense s Phagocytes : neutrophils, monocytes & macrophages s Natural Killer (NK) Cells s lymphocytes s kill cancer and virus infected cells by secreting a protein that lyses their abnormal cell membrane s found in lymph nodes, spleen, bone marrow & blood Non Non-Specific Defenses: Specific Defenses: 2 nd nd Line of Defense Line of Defense Fever: s Phagocytes exposed to pathogens release chemicals that raise body temperature s ↑ body temperature means body defenses are at work s Fever boosts the immune system by: s stimulating more phagocytes to site of infection s increasing body’s metabolism s decreasing some microorganisms’ ability to multiply Non Non-Specific Defenses: Specific Defenses: 2 nd nd Line of Defense Line of Defense Interferon: s A glycoprotein produced by viral infected cells s Released into the bloodstream or intercellular fluid to induce healthy cells to manufacture an enzyme that counteracts the viral infection (prevents nearby cells from producing more virus) s Used to boost the immune system in the treatment of malignancies and neurological disorders such as Multiple Sclerosis (MS) and Hepatitis C Non Non-Specific Defenses: Specific Defenses: 2 nd nd Line of Defense Line of Defense Inflammation : s The body’s reaction to get rid of, or limit the harmful effects of irritants and pathogens s Prevents the spread of damaging agents s Disposes of cell debris and pathogens s Sets the stage for repair...
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- Spring '08
- cells, immune cells