Micro Chapters 14/15/16/17

25 July 2022
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Washing hands regularly with antibacterial agents removes normal microbiota, which may result in
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increased susceptibility to disease.
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commensal bacterium
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may also be an opportunistic pathogen
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transient microbiota
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are present for a relatively short time and cause disease
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normal microbiota (flora)
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do not cause disease
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The major significance of Robert Koch's work is that
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microorganisms causes disease.
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Candida albicans does not normally cause disease because of
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the normal microbiota.
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sporadic
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a disease that affects a population occasionally
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incidence
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number of new cases of a disease
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pandemic
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a disease that affects a large number of people in the world in a short time
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endemic
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a disease that is constantly present in a population
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epidemic
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multiply sites outside the endemic area affected by a disease
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Focal infections initially start out as
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local infections.
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communicable disease
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spread from one host to another, contagious; AIDS, malaria, tuberculosis, typhoid fever, measles, chickenpox, smallpox, rabies
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noncommunicable disease
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not spread; tetanus and botuilism
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acute disease
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develops rapidly but lasts a short time
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chronic disease
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develops slowly but lasts a long time
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subclinical infection
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has no signs or symptoms
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symptoms
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- changes that are felt by the patient - subjective changes - can't measure - pain
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signs
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- objective changes - can be measured - fever - blood pressure - swelling - lesions
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syndrome
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the collection of all symptoms and signs
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predisposing factors
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- climate - genetic background - occupation - lifestyle
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Which of the following diseases can gender be considered a viable predisposing factor?
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urinary tract infection
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Pattern of disease that the patient experience NO signs or symptoms.
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incubation and convalescence
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Spread by a droplet infection
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- diphtheria - the common cold - measles - tuberculosis
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reservoirs of infection
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- a healthy person - a hospital - a sick person - a sick animal
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fomite
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objects
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aerosol
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droplet
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vehicle
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food, water
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vectors
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flies, mosquitoes, ticks
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zoonosis
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- cat scratch disease - Hantavirus pulmonary syndrome - tapeworms - rabies
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Surgical infections account for what number of nosocomial infections?
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20%
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What type of nosocomial infection is likely to arise from inrtavenous catheterizations?
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bacteremia
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Why are invasive procedures likely to increase the risk of nosocomial infections?
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these procedures allow microbes from the skin to enter the bloodstream of the patient
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nosocomial infection
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- acquired during hospitalization - 5 to 15% of all patients - higher % resistant to antibiotics - compromised hosts - patients - most common is urethral with E. coli from catheter
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Pseudomonas bacteria colonized the bile duct f a patient following his liver transplant surgery. This is an example of
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nosocomial infection
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Contributers to the emergence of infectious diseases.
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- antibiotic resistance - climatic changes - new strains of previously known agents - ease of travel
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When aerosols containing pathogens spread disease from a distance of less than 1 meter, it is considered
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Contact transmission
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Considered a major category of transmission of disease...
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contact, vehicle, and vector transmission
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Example of vehicle disease transmission...
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The presences of Listeria on undercooked chicken served for dinner.
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The CDC is located in
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ATLANTA, GA
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Fungal zoonosis that can be transmitted by direct contact...
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Ring worm
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Example of mutualism...
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E. coli within the large intestine
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Which of these statements about exotoxins is FALSE?
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They are resistant to heat.
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Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates.
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The pathogen must be isolated from inculated animals and must be different from the original organism.
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Which of the following is classified as a latent disease
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Shingles
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Malaria is an infectious disease caused by infection with the protozoan. In certain tropical regions malaria is constantly present. We would say that malaria is a _______ disease in these regions.
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Endemic
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MMWR is a publication by the CDC that reports on only emerging diseases.
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False - MMWR = chronicles diseases reported in the entire US
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A host is not considered diseased until an infection changes one state of health
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True
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Reservoirs of infections are always animate objects
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False
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Urinary tract infections are the most common forms of nosocomial infections
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True
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Both normal and transient flora can become opportunistic pathogens
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True
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Endotoxins are also known as
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Lipid A.
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When would endotoxins be released from a bacterial cell?
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When the cell dies
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Which of the following would be the first sign of an infection that resulted in the release of endotoxin?
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Fever
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Why is a release of endotoxin into the bloodstream potentially deadly?
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It can lower blood pressure and cause the patient to go into shock
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Which of the following features is Salmonella prevent it from being phagocytosed?
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Flagella
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Where do Salmonella pathogens grow and replicate in the infected host?
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Inside phagocytes
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Where is the site of Shigella attachment in the host?
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M cells
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How do Shigella cells move between host cells?
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They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another
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What is the etiologic agent of typhoid?
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Salmonella
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A exotoxin that has the ability to kill or damaged host cells is referred to as a
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Cytotoxin
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Which domain of the A-B toxin binds to cell surface receptors on the host cell
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B domain
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How are superantigens different from other types of exotoxins
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Superantigens cause an over stimulation of the host immune system
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A person who attended a picnic earlier in the day develops a very high fever and is unresponsive by the evening, this person most likely has been exposed to a
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Superantigen
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A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a
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Neurotoxin
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How are immune cells able to detect foreign pathogens
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They are able to detect structures on the surfaces of foreign cells that are not found in the host
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How does a capsule help certain bacteria evade detection by the immune system
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The capsule is composed of polysaccharides that are similar to those found in the host thus the immune system does not recognize it as foreign
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Which of the following microorganisms actually grows inside the macrophage
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Tuberculosis bacterium
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Leukocidins
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Molecules that are capable of destroying phagocytes
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How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system
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They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen
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How do capsules enable bacteria to evade the immune system
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Capsules block the complement biding sites on the surface of the
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Certain traits that allow pathogens to create infection and cause diseases are termed
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Virulence factors
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Which of the following enzymes breaks down the glue that holds cells together
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Hyaluronidase
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Antibiotics can lead to septic shock if used to treat
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Gram (-) bacterial infections
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ID50
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Is the dose that will cause an infection in 50% of the test population
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Endotoxins
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- part of the gram (-) cell wall - released when bacteria is killed or dies - lipid A is the toxic portion
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A-B toxin
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Not a membrane disrupting toxin
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Cytopathic effects are changes in host cells due to
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Viral infections
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All of the following are used by bacteria to attach to host cells
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- fimbriae - capsules - M protein - ligands
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The most frequently used portal of entry for pathogens is the
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Mucous membranes of the respiratory tract
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Adherence
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- most bacterial adhesins are glycoproteins or lipoproteins - pathogens have adhesions that bind to host receptors - can be in capsule, on outer membrane, pili, etc.
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The Limulus amoebocyte assay is used to detect minute amounts of endotoxin in drugs and medical devices
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True
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Cytopathic effects, such as inclusion bodies and syncytium formation, are the visible signs of viral infections
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True
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Ergot and aflatoxin are toxins sometimes found in grains contaminated with fungi
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True
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Infections with some viruses may induce chromosomal changes that alter the growth properties of host cells
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True
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Most symptoms of endotoxins can be treated with administration of anti-endotoxin antibodies
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False
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The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of
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Adhesins
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Transit microbiota differ from normal microbiota in that transit microbiota
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Are usually present for a relatively short time
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Epidemiology
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The science that deals with with diseases Acker and how they are transmitted is called
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Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages
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Give new generation sequences to the host bacteria
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Which of the following is NOT a communicable disease
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Tetanus
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Diseases that are referred to as EIDs have only been discovered in the past 50 yrs.
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True
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Antibiotics can kill gram (-) bacteria, but symptoms of fever and low blood pressure can persist because of exotoxins
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...
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Compromised hosts are suffering from suppressed or weak immune systems
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True
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The M protein enhances the virulence of Streptococcus by preventing phagocytosis.
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False
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LD50
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Is the dose that will kill 50% of the hosts infected
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Invasins
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Allow bacteria to penetrate host cell cytoskeleton and become intracellular
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Siderophores
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Chemicals secreted to capture iron and other vital metals
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Exotoxins
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Secreted proteins
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Which non-specific defense mechanism is mismatched with its associated body structure or body fluid?
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mucociliary escalator - intestines
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keratin and tightly packed cells
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skin
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very acidic pH
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stomach
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lysozyme
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tears and saliva
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cerumen and sebum
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ear
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Normal microbiota (lora) provide protection from infection in each of the following ways except
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they produce lysozyme
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If a patient has been exposed to an antigen for the first time, which class of immunoglobulin appears first?
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IgM
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The function of the ciliary escalator is to
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trap inhaled dust and microorganisms in mucous and propel it away from the lower respiratory tract
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The immune system these as chemical messengers for communication
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cytokines
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Which of the following is found in normal serum?
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complement
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Which of the following statements about fixed macrophages is false?
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they develop from neutrophils
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Lysozyme and the antibiotic penicillin have similar mechanisms of actin in that they both cause damage to the bacterial
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cell wall
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How many classes of antibodies are there?
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5
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Innate immunity
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is nonspecific and present at birth
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All of the following protect the skin and mucous membranes from infection except
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HCI
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Which of the following exhibits the highest phagocytic activity?
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macrophages
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A differential cell count is used to determine each of the following except
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the number of red blood cells
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Which of the following terms is mismatched?
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chemotaxis - chemical degradation inside a phagolysosome
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pus
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tissue debris and dead phagocytes in a white or yellow fluid
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diapedesis
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movement of leukocytes between capillary walls cells out of blood and into tissue
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Histamine and kinins cause increased blood flow and capillary permeability.
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True
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Microorganisms that are members of the normal microbiota are also known to cause disease.
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True
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Maturation of stem cells into mature blood cells occurs in the red bone marrow.
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True
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Only dendritic cells produce interleukins.
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False
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Antibodies are found in the gamma fraction of serum.
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True
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Interleukins are a type of cytokine.
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True
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apoptosis
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programmed cell death
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TH (helper - CD4)
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key cell in immunity; bridges the cellular and humoral responses
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plasma (B cell)
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makes antibodies
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opsonization
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coating of bacteria with antibodies
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Which of the following bacterial components would most likely result in B cell stimulation by T - independent antigens?
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capsule
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The presence of which of the following indicates a current infection rather than a previous infection or vaccination?
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IgM
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Which of the following destroys virus-infected cells?
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CTL
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antigen
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a chemical that elicits an antibody response and can combine with these antibodies
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The most abundant class of antibodies in serum is
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IgG
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Large antibodies that agglutinate antigens are
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IgM
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In addition to IgG, the antibodies that can fix complement are
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IgM
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The antibodies that can bind to large parasites are
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IgE
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The majority of the B cells surface immunoglobulins are
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IgD and IgM
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The antibodies found in mucus, saliva, and tears are
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IgA
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B cells are activated by
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a antigen
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Cellular immunity
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- cells are processed in the thymus gland - the cells originate in bone marrow - T cells react with antigens - it can inhibit the immune response
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Pathology
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Study of disease
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Etiology
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Cause of disease
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Pathogenesis
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Manner of disease development
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Infection
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Invasion or colonization of the body by pathogens
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Disease
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Any change from homeostasis
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Virulence
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A measurement of pathogenesis
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Symbiosis
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Relationship between an organism and the host
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Commensalism
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1 benefits 1 unaffected
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Mutualism
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Both organism benefit
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Parasitism
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1 benefits at the others expense