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33 Cards in this Set
- Front
- Back
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The Concept of Immunity
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-Susceptibility: lack of resistance to a disease
-Immunity: ability to ward off disease -Innate immunity: defenses against any pathogen -Adaptive immunity: immunity, resistance to a specific pathogen |
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The Concept of Immunity
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Innate immunity pathogen recognition:
-Host Toll-like receptors (TLRs) attach to Pathogen-associated molecular patterns (PAMPs) -TLRs induce cytokines that regulate the intensity and duration of immune responses |
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Physical Factors
(First Line of Defense) |
Skin
-Epidermis: consists of tightly packed cells with -->Keratin, a protective protein Mucous membranes Mucus: traps microbes Ciliary escalator: microbes trapped in mucus are transported away from the lungs Lacrimal apparatus: washes eye Saliva: washes microbes off Urine: flows out Vaginal secretions: flow out |
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Chemical Factors
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-Fungistatic fatty acid in sebum
-Low pH (3-5) of skin -Lysozyme in perspiration, tears, saliva, and urine -Low pH (1.2-3.0) of gastric juice -Low pH (3-5) of vaginal secretions |
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Normal Microbiota and Innate Immunity
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-Microbial antagonism/competitive exclusion:
-->Normal microbiota compete with pathogens or alter the environment -Commensal microbiota: one organism (microbe) benefits and the other (host) is unharmed -->may be opportunistic pathogens |
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Formed Elements in Blood
(Second Line of Defense) |
Red blood cells
-transport O2 and CO2 Platelets -blood clotting |
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Formed Elements in Blood
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White Blood Cells Granulocytes:
-Neutrophils: phagocytosis, first responder -Basophils: histamine -Eosinophils: kill parasites |
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Formed Elements in Blood
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White Blood Cells Agranulocytes:
-Monocytes: phagocytosis, mature into macrophages -Dendritic cells: phagocytosis, antigen-presenting cell -Natural killer cells: destroy target cells by cytolysis and apoptosis -T cells: cell-mediated immunity -B cells: produce antibodies |
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Differential White Cell Count
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Percentage of each type of white cell in a sample of 100 white blood cells
-Neutrophils: 60-70% -Basophils: 0.5-1% -Eosinophils: 2-4% -Monocytes: 3-8% -Lymphocytes: 20-25% |
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The Lymphatic System
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-Lymph: fluid derived from tissue fluid
-Lymph nodes: site of several immune cells -->pathogens that move through the lymph node can activate immune cells -Spleen: contains lymphocytes and macrophages that monitor the blood -Thymus: site for T cell maturation |
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Phagocytes
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-Phago: from Greek, meaning eat
-Cyte: from Greek, meaning cell -Ingestion of microbes of particles by a cell, performed by phagocytes -Neutrophils, macrophages |
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Phagocytosis
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**Look at diagram on slides!**
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Microbial Evasion of Phagocytosis
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-Inhibit adherence: M protein, capsules
-->Streptococcus pygoenes, S. pneumoniae -Kills phagocytes: Leukocidins -->Staphylococcus aureus -Lyse phagocytes: membrane attack complex -->Listeria monocytogenes -Escape phagosome -->Shigella, Rickettsia -Prevent phagosomelysosome fusion -->HIV, Mycobacterium tuberculosis -Survive in phagolysosome -->Coxiella burnettii |
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Mycobacterium tuberculosis
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-Tubercle bacillus
-Produces no exotoxins or enzymes that contribute to infectiousness -Virulence factors: contain complex waxes and cord factor that prevent destruction by lysosomes or macrophages |
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Epidemiology of Tuberculosis
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-Predisposing factors include: inadequate nutrition, debilitation of the immune system, poor access to medical care, lung damage, and genetics
-Estimate 1/3 of world population and 15 million in U.S. carry tubercle bacillus; highest rate in U.S. occurring in recent immigrants -Bacillus very resistant; transmitted by airborne respiratory droplets |
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Tuberculosis: Course of Infection and Disease
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-Only 5% infected people develop clinical disease
-Untreated, the disease progresses slowly; majority of TB cases contained in lungs -Clinical tuberculosis divided into: -->primary tuberculosis -->secondary tuberculosis (reactivation or reinfection) -->extrapulmonary tuberculosis |
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Primary TB
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-Infectious dose 10 cells
-Phagocytosed by alveolar macrophages and multiply intracellularity -After 3-4 weeks immune system attacks -->Tubercle: granulomas consisting of a central core containing bacilli surrounded by WBCs -->Caseous lesions occur if tubercles break down =heal by calcification |
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Secondary TB
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-If patient doesn't recover from primary tuberculosis, reactivation of bacilli can occur
-Tubercles expand and drain into the bronchial tubes and upper respiratory tract -Gradually the patient experiences more severe symptoms -->violent coughing, greenish or blood sputum, fever, anorexia, weight loss, fatigue -Untreated, 60% mortality rate |
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Extrapulmonary TB
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-During secondary TB, bacilli disseminate to regional lymph nodes, kidneys, long bones, genital tract, brain, and meninges
-These complications are grave |
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TB Diagnosis
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1. In vivo or tuberculin testing (skin test)
-->Mantoux test: local intradermal injection of purified protein derivative (PPD), look for red wheal to form in 48-72 hours 2. X-rays 3. Direct identification of acid-fast bacilli in specimen 4. Cultural isolation and biochemical testing |
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Management and Prevention of TB
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-6-4 months of atleast 2 drugs form a list of 11
-One pill regiment called Rifater (isoniazid rifampin, pyrazinamide) -Vaccine based on attenuated bacilli Calmet-Guerin strain of M. bovis used in other countries |
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Inflammation
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Signs and symptoms
-Redness -Swelling (edema) -Pain -Heat |
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Chemicals Released by Damaged Cells
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Histamine
-vasodilation, increased permeability of blood vessels Kinins -vasodilation increased permeability of blood vessels Prostaglandins -intensity histamine and kinin effect Leukotrienes -increased permeability of blood vessels, phagocytic attachment |
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Step #4-Margination
(Phagocyte Migration and Phagocytosis) |
phagocytes stick to endothelium
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Fever
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-Abnormally high body temperature
-Hypothalamus normally set at 37 degrees Celsius -Gram negative endotoxin cause phagocytes to release interleukin-1 (IL-1) -Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature -Body increases rate of metabolism and shivering which raise temperature -Vasodilation and sweating. Body temperature fails (crisis) |
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Advantages and Disadvantages of Fever
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Advantages
1) increases transferrins 2) increases IL-1 activity 3) produces interferon Disadvantages 1) Tachycardia 2) Acidosis 3) Dehydration 4) 44-46 degrees Celsius fatal |
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Antimicrobial Substances
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-Complement system
-Interferons -Iron-binding proteins -Antimicrobial peptides |
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The Complement System
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-Serum proteins activated in a cascade
-Activated by -->antigen-antibody reaction -->proteins C3, B, D, P, and a pathogen -C3b causes opsonization -C3a+C5a cause inflammation -C5b+C6+C7+C8+C9 cause cell lysis |
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Effects of Complement Activation
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-Opsonization or immune adherence: enhanced phagocytes
-Membrane attack complex: cytolysis -Inflammation: attract phagocytes |
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Some Bacteria Evade Complement
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-Capsules prevent C activation
-Surface lipid-carbohydrates prevent membrane attack complex (MAC) formation -Enzymatic digestion of C5a |
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Interferons (IFNs)
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-IFN-a(alpha) and IFN-b(beta): cause cells to produce antiviral proteins that inhibit viral replication
-Gamma IFN: causes neutrophils and macrophages to phagocytize bacteria |
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Iron-binding proteins
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-Bind iron and deprive bacteria
-->transfer rin -->lactoferrin -->ferritin -->hemoglobin |
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Antimicrobial peptides
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-Over 600 identified
-Lyse bacterial cells -Triggered in response to Toll-like receptor binding |
