microbiology – Test 3; Immunity I-IV – Flashcards
Unlock all answers in this set
Unlock answersSusceptibility |
lack of resistance to a disease |
Immunity |
Ability to ward off disease |
Innate Immunity |
born with; defenses against any pathogen; general first and second line of defense
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Adaptive Immunity |
Resistance to a specific pathogen |
Innate Immunity: Physical First line Defense skin |
cells tightly packed together; dry skin flakes off |
Innate Immunity: Physical First line Defense Mucus Membranes |
Membrane: also epitheal layer Mucus: Viscous glycoprotein material keeps membrane from drying Lacrimal apparatus: tear ducts; tears Cilia: sweep microbes up from lower respiratory tract Others: hair, urine flow, vaginal secretions, defication, vomiting, peristalsis |
Innate Immunity: Chemical First line Defense
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Sebum: fatty acids inhibits microbial growth; secreted by sebacious glands Lysozymes: break down petidoglycan; tears, urine, sweat Gastric Juice: very low pH is inhibitory; Helicobacter pylori-stomach ulcers |
Innate Immunity: Chemical First line Defense
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Urine: low pH; lysozymes Vaginal Secretions: low pH is inhibitory Normal Flora: use nutrients; produce inhibitory compounds; #bacterial cells > #human cells |
Innate Immunity: Second line Defense
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Circulatory system; blood and lymph |
Innate Immunity: Second line Defense Leukocytes |
Neutrophils: phagocytosis Basophiles: Histamine; allergic reactions Eosinophils: selective for parasites Monocytes (Macrophages): best phagocytes |
Innate Immunity: Second line Defense Leukocytes |
Dendritic cells: phagocytosis Natural Killer cells: Destroy target cells *T-cells: cell-mediated immunity *B-cells: produce antibodies *=3rd line defense |
Innate Immunity: Second line Defense Lymphatic System
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Lymph: Fluid Lymphoid Tissue: ex. tonsils Red Bone Marrow: blood cell origin Lymphatic Vessels: carry lymph and blood |
Innate Immunity: Second line Defense Phagocytosis
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Ability to ingest microorganisms
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Bacterial defenses against phages |
capsule toxins biofilm formation: extracellular matrix hide inside phagocyte |
Second Line Defense Inflammation |
Cytokines released; recruit phagocytes Redness/Heat: increased permeability and vasodilation; cells can leave vessel and enter tissue Pain/Swelling: increased blood and pressure; nerve damage |
Second Line Defense Fever |
Cytokines travel to brain: hormone-like molecules; reset (increase) body temp Rate of metabolism increased; shivering Decrease availible Iron Decrease Doubling time of bacteria w/ increased body temp |
Second Line Defense Antimicrobial Substances Complement System |
30+ proteins complement innate and adaptive immunity Proteins kept inactive; due to high potency
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Activated Complement System |
C3a C3b = activated proteins (lower case) Cytolysis: makes holes in bacterial membrane; cell lysis Enhance Inflammation: proteins stimulate histimines that bind to bacterial cell
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Activated Complement System Opsonization |
Opsinization = Enhanced phagocytosis Protein coats bacteria |
Second Line Defense Antimicrobial Subtances Interferons |
Antiviral properties; interfere with viral replication Infected cell releases interferons that bind to healthy cells "paul revere" Healthy cells produce antiviral proteins |
Second Line Defense Antimicrobial Subtances Iron Binding Proteins (IBP) |
IBP keep Fe from siderophores Transferrin: blood in tissue Lactoferrin: milk, saliva, mucus Ferritin: liver, spleen, bone marrow Hemoglobin: RBCs |
Second Line Defense Antimicrobial Substances Antimicrobial Peptides |
Peptides (NOT proteins) produced by host cells Synthesis is triggered by proteins or sugars on a pathogen’s surface broad spectrum |
Second Line Defense Antimicrobial Substances Antimicrobial Peptides: Modes of Action |
Inhibit cell synthesis form pores in pathogen's membrane destroys pathogen's DNA/RNA No bacteria resistant |
Adaptive Immunity |
stem cell splits Humoral: differentiates in bone marrow; B-cell Cell mediated: differentiates in Thymus; T-cell |
Active Humoral Immunity |
produced by host in response to antigen |
Passive Humoral Immunity |
received from donor; breast milk, placental transfer Immune serum; anitivenom |
Antigen (ag) |
substance that generate immune response: |
Types of Antigens |
capsule peptidoglycan flagella bacterial toxins pollen transplanted tissue/blood |
Epitope |
portion of ag that reacts with antibody; aka antigenic determinant |
Hapten |
small molecule with an epitope; immune response only when attached to a large carrier (protein |
Adjuvant |
substance to increase immunogenicity (ability to invoke immune response) |
Antibodies |
a compact globular protein produced in response to an antigen; aka Immunoglobulin |
Antigen binding sites |
recognize and bind to antigenic determinants |
Antibiotic Classes IgM |
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Antibiotic Classes IgG |
follows IgM; most common in serums Functions: Protects fetus/newborn; passive immunity |
Antibiotic Classes IgA |
Found in secretions Function: |
Antibiotic Classes IgD |
Found on surface of some lymphocytes Function: helps activation of lymphocytes |
Antibiotic Classes IgE |
Found on mast and basophil cells Function: Allergic Reactions Parasitic worm infections |
Ag/Ab Binding |
Ab tag pathogens by complement/phagocytes |
Ag/Ab binding Agglutination |
Enhances Phagocytosis (reducing #infectious units); Ag bind 2-3 bacterial cells together |
Ag/Ab binding Opsonization |
enhances phagocytosis; Coats bacteria with antibodies |
Ag/Ab binding complement activation/fixation |
Antibodies act like flags; inflammation and cell lysis |
Ag/Ab binding Antibody-dependent cell-mediated immunity |
attaches to larger target cells (parasites); destruction by: eosinophils: release perforic/lytic enzymes macrophages NK cells
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Antibody Production B-cells |
origin: bone marrow contains specific ab on surface thats binds to specific epitope
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Clonal Expansion |
activated B-cell secretes antibodies that target pathogen |
B-cell Activation T-cell independent |
less common polysaccharide (T-independent ag) has multiple binding sites |
B-cell activation T-cell dependent |
more common B-cell "chews" up antigen MHC class II molecule displays antigen fragments on b-cell surface T-cell confirms antigen and releases cytokines |
Memory Cells |
Clonal selection: b-cells from expansion formed into plasma or memory cells; preventative measure - quicker response
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Activation Location |
B-cells, T-cell, phagocytes interact in lymph tissue |
Antibody effectiveness |
most effective against extracellular pathogens |
Antibody production |
Upon activation: B-cells become plasma and IgM ab first |
isotype switching |
B-cell→IgM→Ig... |
Primary Immune Response |
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Secondary immune Response |
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T-cells Cell-mediated immunity |
fight intracellular pathogens enhanced phahocytosis respond to tumor cells transplant rejection |
T-cells |
oringinate in bone marrow; mature in thymus T-cell receptors recognize specific antigen Activated by "Antigen presenting cells" (b-cell displaying antigen) |
T-cell Classes T-helper (TH) cells |
release cytokines that activate b-cells against extracellular pathogens; antigen interaction: MHC Class II |
T-cell Classes Cytotoxic (TC) cells |
Antigen interaction: MHC Class I; marks cell as "self" ags tag infected cells; non-self Controlled destruction of infected cells; shrivel |
T-cell Classes T-Suppressor (TS) cells |
recognize "self" antigens Immune Tolerance: |
T-cell Classes T memory (TM) cells |
Recognize previous T-dependent antigens (extracellular) Results in fast secondary immune response |
Non- T/B immune cells Natural Killer cells |
Non-phagocytic lymphocytes; induce apoptosis (controlled cell death) Additional help: virus infected cells/tumor cells
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Measurement of Immune Response |
Blood cell count: # WBC, RBC, platlets Antibody Count: Titer test (#abs) Cytokine Levels Agglutination Reaction: blood typing, prego Hypersensitivity: allergen skin test
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Other uses for abs |
Vaccines ID of microbes Immunoblotting |
Immune System problems Autoimmunity |
immune reaction against self; sees host cells as pathogenic ex. MS, Rheumatoid arthritis, Type I diabetes |
Immune System problems Ineffectiveness |
occurs when some pathogens are not killed; hide inside host ex. mycobacteria "TB", legionella, listeria Biofilms also resistant |
Immune System problems loss-all/part |
AIDS Genetic disorders = reduced life expectancy (often before 5) Severe combined immunodeficiency (low B and T cell levels) |
AIDS |
Diagnosis: appearance of second infection; antibody titer against HIV Retrovirus HIV infects (TH) cells; specific immunity adapted immunity wiped out susceptibility of secondary infection is main COD |
Immune System problems Hypersensitivity |
excessive immunological response to antigen Allergy: immune response to allergen |
Type I Immediate/anaphylactic Hypersensitivity |
fast; 5-30 min ex. hay fever/bee sting allergies |
Type II Antibody Dependent cytotoxic Hypersensitivity |
antibody combines with cell ex. blood group incompatibilty Rh factor
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Type III Immune-complex hypersensitivity |
Immune complex: Small particulate ab-ag combination; stimulates rest of immune system causing tissue/cell destruction |
Type IV Delayed or Cell-mediated hypersensitivity |
1-3 days after exposure ex. TB skin test, poison ivy |
Koch' Postulates |
1. Same pathogen must be present in every case of the disease 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible lab animal |
Pathogenicity |
ability of an organism to cause disease possess weapons aka virulence factors |
Infectious Dose |
# of bugs required to cause infection |
Acute Infection |
short/severe ex. strep throat |
Chronic Infection |
Prolonged ex. TB |
Fulminating infection |
sudden/intense ex. meningitis |
Primary Infection |
initial infection Flu/HIV |
Secondary Infection |
occurs after primary by oppurtunisitic pathogens ex. pneumoniae following flu |
Bacterimia |
presence of bacteria in blood Septicemia: bacteria growing in blood |
Steps to cause disease Entry Portal of Entry |
Membranes/skin Parenteral: direct deposition beneath skin or mucous membranes *most pathogens have preferred POE |
Steps to cause disease Entry Adherence |
Adhesins (Ligands): bind pathogen;to specific receptors in host ; |
Steps to cause disease Entry Penetration |
Active: pathogen has own mechanism for penetration Passive penetration: organism penetrates tissue due to wound, burn, insect bite, animal bite, etc. |
Host: Immune recognition of epitopes on pathogen surface |
Pathogen: capsule hides cell surface; resist phagocytosis; eleminates unnecessary components; Antigenic phase variation: bacteria changes ags Molecular Mimicry: pathogens decorate surface that mimic host cell surfaces ; |
Host: Leukocytes |
Pathogen: secretes Leukocidin to kill leukocytes/ some live inside leukocyte |
Bacterial Pathogens Penetration into Cytoskeleton |
bacteria use Actin for movement in cytoskeleton ; |
Host: Immunoglobulins |
Pathogens secrete protease to digest antibodies ex. Ig protease |
Host: Low Nutrient Level |
Pathogens: produce siderophores; "Fe boomerang" Select best habitat for colonization; richer nutrient area |
Host: Protection from tissue surface or mucus layer |
pathogen: secrete enzymes to break down surface |
Normal Flora |
pathogen: competes for nutrients adapts to less favorable nutrients |
Damage to Host Cells by Bacterial Pathogens Direct Damage Exoto |
Exotoxins: produced by bacteria; secreted proteins- small amount needed ex. tetanus, botulism Endotoxins: within;LPS released upon death; GRAM NEGATIVE ex. Typhoid fever and N. meningitidis ; |
Exotoxins |
;Source: Gram + Relation to microbe: by-products of cell Chemistry: Protein Fever?;No Neutralized by Antitoxin? Yes Lethal Dose: small |
Endotoxins |
Source: Gram ; Relation to microbe: outer membrane Chemistry: Lipid A Fever?;Yes Neutralized by Antitoxin? No Lethal Dose: ~large |