Microbiology Block 1 – Flashcards

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Sterilization
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Kills everything
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Disinfection
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does not kill endospores
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Sanitization
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cleansing technique that mechanically removes micro-organisms- not sterile but decreases # of microbes
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Degermation
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reducing the number of microbes in human skin
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Microbicide
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kills microbes
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Microbistatic agent
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temporarily prevents multiplication
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Microbial death
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The permanent loss of reproductive capability even in optimal conditions
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  • number of microbes
  • nature of microbes in the population
  • temperature and the pH
  • concentration or dosage of agent
  • mode of action of agent
  • presence of solvents, organic matter, or inhibitors

 

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Factors that affect the death rate
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  • heat 
  • radiation
  • cold
  • dessication

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Physical control of microbes is accomplished by what methods.
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Moist heat under pressure/autoclave
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Which type of heat is the most effective and what method uses this type of heat?
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Lowest temperature required to kill ALL microbes in ten mintues
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What is the thermal death rate?
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Pasteurization
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Heat applied to liquids to kill potential agents of infection and spoilage
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Cold Sterilization
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Sterilizing using radiation instead of heat
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Ionizing radiation penetrates much deeper, non-ionizing radiation is UV light and doesn't penetrate past the surface
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What is the difference between ionizing radiation and non-ionizing radiation?
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Filtration
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What method is used to sterilize the air in hospital isolation rooms?
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  1. Cell Walls
  2. Cell membranes
  3. DNA or RNA synthesis
  4. Protein function

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What are the four cellular targets of anti-microbials?
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  • most bacterial
  • vegetative cells
  • fungal spores
  • enveloped viruses
  • yeast
  • protozoan
  • trophozoites

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What type of microbes are least resistant?
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Bacterial endospores
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What type of microbes are most resistant?
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  • Pseudomonas sp.
  • Mycobacterium
  • TB
  • Staphylococcus aureus
  • Protozoan cysts

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What type of microbes have moderate resistance?
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Glutaraldehyde and hydrogen peroxide
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Which chemical agents are the closest to ideal agents?
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Halogens
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What class of chemical agents do chlorine and iodine belong to?
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Phenolics
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What class of chemical agents does Lysol belong to?
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Dissolve membrane lipids, disrupt cell surface tension and denatures proteins
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What is the mechanism of action of alcohols?
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Chemiclave
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An automatic ethylene oxide sterilizer
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Mechanism of action of Hydrogen Peroxide
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Germicidal affects are due to the direct and indirect actions of oxygen which forms free radicals that are highly toxic to microbes.
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Low level disinfection only
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Detergents are useful for which level of antimicrobial effects?
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Silver and Mercury
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What types of heavy metals have been used for microbial control?
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Aldehydes-glutaraldehyde;

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Sterile equipment that can not tolerate high heat

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What class of chemical agents does Cidex belong to? What is is used for?
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Chemotherapy
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Any chemical used in the treatment, relief, or prophylaxis?
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Prophylaxis
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Any chemical used to treat or prevent disease (meds used to prevent disease)
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Antibiotics
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Natural substances produced by micro-organisms that can inhibit or destroy other microbes?
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Selective toxicity
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Kills microbial cells without damaging host cells
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Narrow spectrum
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Limited range of microbes affected by the drug
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Broad spectrum
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Large range of microbes affected by the drug
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Mechanism of action of antimicrobials
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Inhibition of cell wall, DNA/RNA function, protein synthesis and interference with cell membrane structure or function are the mechanism of what?
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Penicillins and Cephalosporins
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Which classes of drugs affect the bacterial cell wall?
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Flouroquinolones, Rifampin, and antiviral drugs
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Which classes of drugs affect DNA/RNA synthesis?
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;Tetracyclines, aminoglycosides,erythromycin
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Which classes of drugs affect protein synthesis?
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Polymyxins and antifungals
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What classes of drugs affect cell membrane?
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Sulfonamides
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Antibiotics that interfere with metabolic processes.
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Beta Lactam ring
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What is unique about the structure of penicillin
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They develop enzymes to break the beta lactam ring
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How do enzymes become resistant to penicillins?
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  • Streptococcus
  • Staphylococcus
  • Syphilis
  • some gram negative rods

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Penicillins are effective against what type of microbes?
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Chemical that inhibits beta-lactamase enzymes found in augmentin
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What is clavulonic acid? What drug is it found in?
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Cephalosporins
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What group on antibiotics account for the majority of all antibiotics administered?
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4 Generations

1st generation: ;gram positive organisms

2nd, 3rd, and 4th: gram negative organisms

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How many generations of cephalosporins are there and what is significant about those generations?
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Streptomycin and Gentamycin

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What are two examples of aminoglycosides
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GI disruption of normal flora and staining of teeth
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What are the limiting factors of tetracyclines?
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  • Sulfonamides
  • Trimethoprim
  • Dapsone
  • Fluoroquinolone

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Which drugs are synthetic rather than natural antibiotics?
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  • Amphoteracin B
  • Nystatins
  • Azoles

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Which drugs are used totreat fungal infections?
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  • Climdamycin
  • Azithromycin
  • Rifampin
  • Vamomycin
  • Erythromycin
  • Clarithomycin

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Which drugs are classified as macrolides?
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  • Quiniines
  • Metronidazole

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What drugs are used for protozoan infections?
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Interfere with their metabolism so they are weakened and are able to be excreted from the body
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What is the mechanism of action of drugs used for helminth infections?
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Inhibit viral penetration, multiplication, or assembly
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What is the mechanism of action of antivirals?
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  1. Drug inactivation
  2. Decrease permeability/increased elimination
  3. Change of metabolic pattern
  4. Change in drug receptors

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How is drug resistance acquired (4 ways)?
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Natural Selection
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When resistant microbes survive this is known as_______.
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  1. Direct toxicity to organs
  2. Allergic responses
  3. Changes to normal flora/superinfection

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What are 3 categories of host-drug reactions?
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  • The nature of the microbe
  • The susceptibility of the microbe
  • Overall medical condition of the patient
  • Toxicity to the drug

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What is the most important consideration in selecting a medication?

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Minimum inhibitory concentration (MIC)
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The smallest effective dose of a drug against a specific microbe.
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Therapeutic Index (The smaller the TI, the more risk of toxicity to the patient)
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The ration of the toxic dose to the effective dose
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True Pathogen
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A pathogen that will cause disease in an otherwise healthy person.
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Opportunistic pathogen
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A pathogen that will cause disease in an immune compromised person
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Normal Flora
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Beneficial bacteria that are present on the skin, in the GI, upper respiratory tract and GU tracts
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  • Skin
  • mouth
  • upper respiratory tract
  • GU

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Where are staphylococcus spp found?
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  1. portal of entry
  2. invasion of Tissue
  3. portal of exit

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What are the 3 primary events in the infectious process?
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Predominantly in the GI tract and a small amount in the urinary tract
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Where are coliforms found?
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Infectious dose
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The amount of pathogen required to cause disease in a host.
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  • Fimbriae
  • Capsules
  • Spikes
  • Hook
  • Flagella

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What are the mechanisms of adhesion of pathogens?
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Exoenzymes

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Enzymes secreted by the pathogens that damage tissues and promote invasion
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Endotoxins
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Chemicals secreted when the pathogenic cells lyse
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Exotoxins

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Proteins secreted by active gram positive or negative bacteria as specific symptoms.
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Localized infection
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An infection that stays in the portal of entry system
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Systemic infection
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Infection that spreads to several areas
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Focal infection
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Infection that stays in the portal of entry but releases toxins that effect other organs
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Sign
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Objective finding noted by the observer
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Symptoms
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Subjective findings reported by the patient
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Syphillis

Toxoplasmosis

Others (HepB, HIV, chlamydia)

Rubella

Cytomegalovirus

Herpes Simplex Virus

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What are some pathogens that are able to cross the placenta? (STORCH)
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  • Respiratory
  • Salivary
  • Skin scales
  • Fecal
  • Urogenital Tract
  • Blood

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What are some common portals of exit?
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No
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Is the portal of exit for pathogens always the same as the portal of entry?
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Latency
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A pathogen remains in the body in a dormant state but it may still be shed and the person is a chronic carrier.
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Sequale
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Long term or permanent damage to tissues or organs by a pathogen
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Prevalence
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The number of existing cases in certain populations
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Incidence
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The number of new cases compared to the general healthy population
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Mortality
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Total number of deaths in a population due to a certain disease.
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Morbidity
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Total number of disease cases afflicting members of a population.
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Endemic
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The steady frequency of the disease over a long period of time in a certain geographical area
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Epidemic
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The prevalence of a disease is increased in a certain area beyond what is expected
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Pandemic
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Disease that has spread across continents
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Disease Carrier
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An asymptomatic person who carries the pathogen and is able to transmit it.
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Vector
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An infected insect that carries and transmits a disease.
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Fomite
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Inanimate object that harbors and transmits pathogens
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Nosocomial infection
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Disease that is acquired during a hospital stay
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  • respiratory
  • urinary tract
  • surgical incisions

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What are the most common sites of a nosocomial infection?
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First line - physical, chemical, genetic barriers

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Second line - inflammatory response, interferons, phagocytosis

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Third line -acquired/specific immunity

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What are the three lines of host defense?
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First and second lines of defense
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Which lines of defense are inborn/innate?
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Third line
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Which line of defense is acquired?
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Physical barriers

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Skin, rapid regeneration of mucous membranes, nasal hairs, ciliary defense in the respiratory tract, flushing by saliva, tears, sweat, vomiting, defecation, and urination are all examples of what type of barriers?
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Chemical barriers
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Sebaceous secretions, stomach acid, lysozyme in tears, lactic acid in sweat are all examples of what type of barriers?
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Genetic defenses
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What type of defenses are the following:

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  • Some pathogens can only infect certain species
  • Some hosts are genetically immune to the diseases of other hosts
  • Some genetic differences exist in susceptibility

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  1. Surveillance of the body
  2. Recognition of foreign material
  3. Destruction of foreign material

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What three functions is the immune system responsible for?
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Markers
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Proteins and/or carbohydrates that enable the immune system to identify a foreign particle.
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Kochs' postulate
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A theory to prove that a certain microbe caused the disease
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  • reticuloendothelial system
  • extracellualr fluid
  • bloodstream
  • lymphatic system

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Which body compartments are involved in immune function?
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Bloodstream and lymphatic system
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What two systems are included in the circulatory system?
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Lymphocyte and monocytes
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Which cells are agranulocytes?
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Neutrophils, Basophils, Eosinophils
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Which cells are granulocytes?
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Macrophages - differentiated from monocytes
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Which cells are the largest phagocytes and what is their origin?
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B-cells and T-cells
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What type of cells do lymphocytes differentiate into?
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Eosinophils
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Which granulocytes destroy eukaryotic pathogens especially helminth worms and fungi

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Third line of defense - specific/acquired immunity
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What role do lymphocytes play in the immune system.
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B-cells
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Which cells are involved in humoral immunity?
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T-cells
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Which cells are involved in cell-mediated immunity?
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  • phagocytic and killing functions
  • processing foreign material and presenting them to lymphocytes
  • secreting substances that activate other cells of the immune system (cytokines, interleukins)

 

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What functions are macrophages responsible for?
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Diapedesis
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Ability to migrate out of the bloodstream into tissues
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Chemotaxis
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Process of leukocyte migration to the site of inflammation by following chemical stimuli
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Lymphatic system
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What system provides these functions:

 

 

  • provides a route for return of extracellular fluid to the circulatory system
  • acts as a drain-off system for the inflammatory response
  • renders surveillance, recognition, and protection against foreign material through the use of lymphocytes, phagocytes and anibofdies

 

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From plasma and circulates by skeletal muscle contraction
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Where does lymph come from? How is it circulated?
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  • Thymus
  • Spleen
  • Gi tract (GALT)
  • Tonsils

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Where in the body is lymphoid tissue?
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  • mobilize and attract immune components to the site of the injury
  • set in motion mechanisms for tissue repair and clear away harmful substances
  • destroy microbes and block their further invasion

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What are the functions of the inflammatory response?
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Inflammatory response
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A reaction of any traumatic event in the tissues?
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  • Rubor - redness
  • Calor - warmth
  • Tumor - swelling
  • Dolor - pain

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What are the 4 classic signs and symptoms of inflammatory response?
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Pyrogens

  • exogenous (pathogens, blood, vaccines)
  • endogenous (liberated by WBC's during phagocytosis- interleukin 1 and tumor necrosis factor)

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What substances initiate a fever? What are some examples?
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Fever
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This inhibits multiplication of pathogens, impedes nutrition of bacteria, increases hosts metabolism, and stimulates immune reactions
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  • Neutrophils
  • macrophages (have larger role in immune system than neutrophils)

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What cells are considered phagocytes?
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Histocytes

(langerhans in skin, kupffers in liver, alveolar in lungs)

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Specialized macrophages that remain in certain tissues.
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Phagocytes
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Type of cells that survey tissue for microbes, remove damaged tissue, and extract antigens from foreign material.
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Interferons

(alpha, beta, and gamma)

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A family oaf proteins produced by leukocytes and fibroblasts that inhibit the reproduction of viruses by degrading viral RNA or blocking synthesis of viral proteins
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Complement system
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A complex defense system with multiple proteins involved that produce a cascade reaction
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Formation of a membrane attack complex to make holes in the cell membrane of bacteria, cells an enveloped viruses
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What is the final result of the complement system?
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  1. Initiation
  2. Amplification
  3. Membrane attack

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What are the 3 stages of the complement cascade?
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the substance that initiated the cascade reaction
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What is the major difference between the 3 complement pathways
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Interferon
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A/an _______ is produced in response to viruses, RNA, immune products and other antigens. It binds to cell surfaces and induces a change in genetic expression. It inhibits the expression of cancer genes and has tumor suppressor effects.
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  1. specificity to the antigen;
  2. memory

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What are the two features that most characterize the Third line of defense- acquire specific immunity?
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Third Line - acquire specific immunity
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The following stages belong to what line of defense?

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  • development of the lymphocyte system
  • processing of antigens and clonal selection
  • activation of lymphocytes ;and clonal selection
  • antibody production
  • cell-mediated immunity

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Receptors
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Protein or carbohydrate markers on the outside of the cell that receive and transmit chemical messages to aid in cellular development
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Clonal Selection Theory
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Preprogrammed lymphocyte specificity, existing in the genetic makeup before an antigen has ever entered the system. Each genetically different type of lymphocyte expresses a single specificity- undifferentiated lymphocytes undergo a continuous series of divisions and genetic changes that generate hundreds of millions of different cell types.
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Immune Tolerance
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The elimination of any clones that may be specific for self cells
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Immunoglobulins
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Large glycoprotein molecule that serves as the specific receptors of B-cells and as antibodies
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Antigen binding site
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Site that is highly variable in shape to fit very specific antigens; at the end of the Y structure on the Ig.
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MHC (Major Histocompatabilty Complex)
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Receptors found on all cells except RBC's
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Class I receptor
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Type of MHC receptor that displays unique characteristics of self molecules and regulation of immune reactions and is required for T lymphocytes
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Class II receptors
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Type of MHC receptors that recognize and react with foreign antigens; located primarily on macrophages and B cells; involved in presenting antigen to T cells
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Class III receptors
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Type of MHC receptor that is secreted complement components, C2 and C4
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Antigen
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What provokes an immune reaction and is perceived as foreign by the immune system.
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Antigenic determinant
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Small molecular group of an antigens that is recognized by lymphocytes. It is the primary signal that the molecule is foreign.
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Hapten
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Small molecules that are usually not antigenic unless attached to a larger carrier.
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Allergan
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An antigen that provokes allergic reactions
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Most are T-cell dependent (only a few can interact with B-cells directly)
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Are most antigens T-cell dependent or do they act directly with b-cells.
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Processed by phagocytes (dendrites) called antigen presenting cells (APC)
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How is an antigen processed?
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APC (Antigen Presenting Cells)
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What alters an antigen and attaches it to its MHC receptor where it can be presented to the B and T-cells
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Interleukens
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Peptides that carry signals between leukocytes
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  1. Interleukon-1 is secreted by APC to activate T-helper cells
  2. Interleukon-2 is produced by T-helper cells to activate B and other T cells
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How are interleukens involved in antigen processing and presenting?
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They enter the cell cycle in preparation for mitosis and clonal expansion. Division gives rise to plasma cells that secrete antibodies and memory cells that can react to the same antigen later
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What happens to the B-cells once they are activated by Interleukon-2?
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Fab - antigen binding fragment

and

Fc - crystalizable fragment that binds to various cells and molecules of the immune system

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What two fragments make up the structure of an antibody
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Antibodies
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What has functions of opsonization, neutralization, agglutination, and fixation
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Opsonization
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Process whereby antigens become coated with specific antibodies so that they will be more readily recognized by phagocytes to dispose of them
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Neutralization
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Process whereby antibodies fill the surface of receptors on a microorganism to prevent it from functioning normally
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Agglutination
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Process of cross-linking cells into larger clumps
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Complement Fixation
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The interaction of an antibody with complement can result in the specific rupturing of cells and some viruses.
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5
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How many classes of immunoglobulins are there?
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IgG
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Which class of immunoglobulins is the most prevalent?
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IgM
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Which class of immunoglobulins is the first responder with an initial antigen encounter?
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IgA
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Which class of immunoglobulins is in many secretions of the body including breast milk?
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IgM
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Which class of immunoglobulins has the largest molecules?

 

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IgG
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Which class of immunoglobulins are produced by memory B-cells in a second exposure?

 

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IgE
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Which class of immunoglobulins interact with mast cells and basophils and is involved in allergic response?

 

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Cell-mediated immunity
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Rather than making antibodies to control foreign antigens, the T cells act directly against antigens. This is known as what type of immunity?
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  1. Helper
  2. Suppressor
  3. Cytotoxic
  4. Delayed Hypersensativity

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What are the 4 types of T-cells?
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CD2
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What receptor is common to all T-cells?
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CD4
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What type of receptor do T-helper cells have?
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CD8
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What type of receptors do T-cytotoxic cells have?
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T-helper 
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What is the most prevalent T-cell?
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HIV depresses and destroys the T-helper cells
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How does a patient with HIV become immunosuppressed?
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T-helper cells (CD4)
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Which type of T-cell is the conductor of the immune response by assisting other T and B cells. It reacts directly by receptor contact and indirectly by releasing cytokines such as interleukin-2
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T-cytotoxic cells (CD8)
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This type of T-cell mounts a direct attack on foreign receptor by secreting perforins that creates pores in the cells membrane, lysing it.
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T-suppressor cells (T helper 2)
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This type of T-cell inhibits the action of other T and B-cells and regulates the immune response by producing protein inhibitors that prevent lymphocytes and macrophages from reacting with antigens.
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T-delayed hypersensitivity cells
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This type of T-cell is responsible for allergies occurring several hours/days after contact such as TB reaction test.
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Natural Immunity
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Acquired immunity as part of natural experiences
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Artificial Immunity
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Immunity acquired through a medical procedure such as a vaccine
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Active Immunity
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Immunity that results when a person is challenged with antigen that stimulates production of antibodies
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Passive Immunity
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Preformed antibodies are donated to an individual
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Natural Active Immunity
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Immunity that is the result of an infection and recovery
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Natural Passive Immunity
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Type of immunity that is the result of pregnancy and lactation
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Artificial Active Immunity
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Type of immunity the result of a vaccination
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