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105 Cards in this Set
- Front
- Back
Define Normal Microbiota |
colonize the surfaces of the body without normally causing disease |
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Resident Microbiota |
stay through the person's entire life |
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transient microbiota |
stay in the body temporarily. Could be dislodged by competition, the body's defenses, or chemical and physical changes |
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most resident microbiota are: (type) |
commensal |
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What do commensal resident microbiota do? |
feed on excreted cellular wastes and dead cells |
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how do we acquire normal microbiota? |
through the birthing process and in the first stages of life (the womb is anexic) |
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Opportunistic Pathogens |
normal microbiota or other normally harmless microbes that can cause disease under certain circumstances |
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What provides opportunities for opportunistic pathogens? |
1. introduction of normal microbiota to an unusual site in the body 2. immune suppression 3. Changes in normal microbiota |
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microbial antagonism |
when normal microbiota take up space and use up the nutrients, it makes it less likely that another species could invade |
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reserviors of infection |
sites where pathogens are maintained as a source of infection |
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zoonoses |
diseases that spread naturally from their usual animal hosts to humans |
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how can a human acquire zoonoses? |
direct contact wi/ animals or their waste/ eating the animal/ blood-sucking anthropods |
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two types of human reserviors |
humans with active diseases carriers |
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examples of nonliving reserviors |
soil, water, and food |
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why are human infections with zoonoses difficult to irradicate? |
sheer number and types of reserviors |
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do humans serve as reserviors for animals? |
not typically |
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what are human reserviors: carriers? |
people with no obvious symptoms before or after an obvious disease. May be infected with no symptoms for years |
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how do nonliving reservoirs become reservoirs? |
usually because they become infected by feces or urine |
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three basic modes of transmission |
contact transmission vehicle transmission vector transmission |
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transmission |
from a reservoir or a portal of exit to another host's portal of entry |
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direct contact transmission |
typically involves body contact between hosts |
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examples of direct contact transmission |
person-to-person touching, kissing, sex, biting, scratching mother-to-fetus self-inoculation |
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indirect contact transmittion |
pathogens spread from one host to another by fomites |
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fomites |
inanimate objects that are inadvertently used to transfer pathogens to new hosts |
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Define droplet transmission. What type of transmission is it under? |
droplets are expelled when we exhale, sneeze, cough, etc. Considered contact transmission if it travels less than 1m |
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vehicle transmission |
the spread of pathogens via air, drinking water, and food, as well as bodily fluids being handled outside the body |
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airborne vehicle transmission |
pathogens that travels more than 1m to respiratory mucous of new host |
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what is significant about waterborne vehicle transmission? |
important in the spread of GI illnesses |
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types of vehicle transmission |
airborne waterborne foodborne bodily fluid transmission |
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vectors |
arthropods that transmit diseases from one host to another |
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biological vectors |
-transmit pathogens -serve as a host for pathogens to replicate -pathogens can replicate within a biological vector, then enter new host from a bite. |
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mechanical vectors |
not required as a host, only passively carry pathogens to no hosts on their feet or other body parts ie- houseflies and cockroaches |
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what is the most common and most frequently used portal of entry? |
respiratory tract |
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contamination |
presence of microbes in or on the body |
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infection |
a successful invasion of the body by a pathogen (may or may not result in disease) |
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what are the three major portals of entry |
skin mucous membranes placents |
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parenteral port of entry |
not a portal of entry but a means by which the portals can be circumvented. pathogens are directly deposited |
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adhesion |
the process by which microorganisms attach themselves to cells and organisms must adhere to host cells if they want to infect them |
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concerning adhesion, what can inhibit an infection? |
blocking or changing the ligand or receptor |
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disease |
~when parasitic injury is significant enough to interfere with the normal functioning of the body
~any change from a state of health |
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sympom |
subjective characteristics of a disease than can be felt by a patient |
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signs |
objective manifestations of the disease that can be observed or measured by others |
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syndrome |
group of symptoms and signs that collectively characterize a particular disease or abnormal condition |
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asymptomatic infections |
go unnoticed because they have no symptoms |
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stages of infectious diseases |
-incubation period -prodromal period -illness -decline -convalescence |
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pathogenicity |
the ability of a microorganism to cause disease |
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virulence |
the degree of pathogenicity |
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does pathogenicity or virulence tell us how sever the disease is? |
no. |
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virulence factors allow the pathogen to: |
-interact with and enter host -adhere to host cells -gain access to nutrients -escape detection or removal by the immune system |
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types of virulent factors: |
adhesion factors biofilm formation extracellular enzymes toxins antiphagocytic factors |
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how to extracellular enzymes help pathogens? |
enables them to dissolve structural chemicals in the body and maintain an infection, invade further, and avoid body defenses |
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examples of extracellular enzymes |
Hyaluronidase and collagenase coagulase kinases |
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toxins |
chemicals that either harm tissues or trigger host immune responses that cause damage |
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difference between toxins and extracellular enzymes? |
no clear - many enzymes are toxic and many toxins have enzymatic action |
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toxemia |
toxins enter the bloodstream and are carried to other parts of the body |
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two types of toxins |
exotoxins and endotoxins |
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exotoxins |
proteins produced by gram-positive and -negative bacteria that detroy host cells or interfere with host metabolism - cytotoxins, neurotoxins, and enterotoxins |
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endotoxins |
-only gram-neg -Lipid A released when cells die and can stimulate the body to release chemicals that cause a bunch of issues and can potentially be life-threatening |
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the longer a pathogen remains in a host... |
...the greater the damage and the more severe the disease |
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What do WBCs do to limit the extent and duration of infecitons? |
engulfs and removes pathogens via phagocytosis |
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what do capsules do? |
make the organisms slippery. can be made of things found in the body |
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antiphagocytic chemicals |
some prevent fusion of lysosome and phagosome, some inhibit phagocytosis, soem directly destroy phagocytic WBCs |
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incidence |
the number of new cases of a disease in a given area or population during a given period of time |
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prevalence |
the total number of cases, both new and already existing, in a given area or population during a given period of time |
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endemic |
a disease that normally occurs continually at a relatively stable incidence within a given population or geographical area |
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sporadic |
only a few scattered cases occur within an area |
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epidemic |
when a disease occurs at a greater number than usual |
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pandemic |
when an epidemic occurs simultaneously on more than one continent |
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Healthcare associated infection |
infections acquired by patients or healthcare workers while they are in health care facilities |
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types of HAIs |
exogenous endogenous iatragenic |
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Exogenous HAI |
pathogen acquired from a healthcare environment |
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endogenous HAI |
arise from opportunistic normal microbiota within the patient due to factors within the health care setting |
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iatrogenic HAI |
results from modern medical prodecures |
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superinfections |
result from the use of antimicrobial drugs that inhibit some resident microbiota and allow others to survive |
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factors that result in HAIs |
-presence of microorganisms in hospital environment -immunouncompromised patients -transmission of pathogens between staff and patients and among patiens |
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species resistance |
resistance due to the cells and physiological processes of humans that are incompatible with those of most plant and animal pathogens |
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how do humans show species resistence? |
dont have the correct temp or ph for the path to survive // dont have the correct receptors |
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first line of defense |
external physical barriers to pathogens |
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second line of defense |
internal and composed of protective cells, bloodborne chemicals, and the processes that inactivate or kill invaders |
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third line of defense |
responds against unique species or strains of pathogens |
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dermicidins |
broad-spectrum antimicrobials found in eccrine sweat glands |
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what in skin hurts pathogens? |
salt, dermicidins (antimicrobial) , lysozyme (destroys cell wall) |
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what does sebum do? |
helps keep skin pliable and less likely to break or tear AND lowers the ph of skin to a level inhibitory to many bacteria |
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lacrimal apparatus |
group of structures that produce and drain away tears that join the nasal mucus and flow into the pharynx |
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what do tears contain to hurt pathogens? |
lysozyme and defensins
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what does mucous contain to hurt pathogens |
lysozyme and defensins |
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how does normal microbiota help with dealing with pathogens? |
competes with new pathogens by consuming all the space and nutrients // change ph to make it uninhabitable // stimulate body's second line of defense // provide vitamins |
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antimicrobial peptides |
(defensins) you can find them on skin, mucous membranes, and neutrophiles and they are triggered by sugar and protein molecules on the external surfaces of microbes |
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where are the majority of the second line defenses created/located? |
blood |
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there is overlap between the first and second lines of defense |
:) |
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plasma |
includes iron-binding proteins transferrin and ferritin which transport and store iron for humans, but they sequester iron from microbes |
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three types of formed elements |
erythrocytes, platelets, and leukocytes |
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erythrocytes |
carry oxygen and carbon dioxide in the blood |
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platelets |
involved in blood clotting |
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leukocytes |
WBCs involved in defending the body againts invaders |
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granulocytes |
have large granules in their cytoplasm that stian different colors depending on the type basophils, eosinophils, neutrophils |
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basophils |
not phagocytic can migrate from bloodstream to tissue release inflammatory chemicals which influence the tone and diameter of blood vessels |
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eosinophils |
phagocytic can migrate from bloodstream to tissue defend against parasitic worms play role in allergic reactions |
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neutrophils |
phagocytic rapidly move from bloodstream to tissue |
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agranulocytes |
cytoplasm appears uniform under a light microscope lymphocytes, monocytes |
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lymphocytes |
most involved in adaptive immunity |
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monocytes |
leave the blood and mature into the phagocytic cells called macrophages (phagocytic cells) |
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phagocytosis |
transporting a solid substance into a eukaryotic cell |
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6 stages of phagocytosis |
-chemotaxis -adherence -ingestion -maturation -killing -elimination |
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opsonization |
the coating of a pathogen with proteins that help to increase phagocytosis - increases the number and kinds of phagocyte binding sites on a microbe's surface |