Chapter 13 (lecture microbe-Human interactions Flashcards
Normal Microbiota
microbes that permanently colonize
Transient Microbita
Present periodically
sites known to habor microbota
skin and adjacent mucous membrane, upper respiratory tract, gastrointestinal tract, including mouth, external genitalia, vagina, external ear canal, external eye
Pathogens
disease-causing microorganisms
True pathogens
make anbody sick
opportunistic pathogens
take advantage of any situation
Pathology
study of the cause, manner, and results of disease
Factors That Weaken Host Defenses and Increase Susceptibility to Infection
-Age: the very young and the very old
-Genetic defects in immunity and acquired defects in immunity (AIDS)
-Pregnancy
-Surgery and organ transplants
-Underlying disease: cancer, liver malfunction, diabetes
-Chemotherapy/immunosuppressive drugs
-Physical and mental stress
Other infections
What is the first step of an infection?
getting in (portal of entry)
What are ways of portal of entry?
-skin
-mucous membrane
-GI tract
-Respiratory
-urogenital
What is the second step of an infection?
staying in (attaching firmly and negotiating the microbe)
what are the ways for the infection to stay?
fimbriae, capsules, and spikes (virsues)
What is the third step of an infection?
surviving host defenses
What are the antiphagocytic factors of surviving host defenses?
-leukocidins (toxic to white blood cells)
-capsules
-survive within
-epigenetic changes to host
What is the fourth step of an infection?
Causing Disease
What are the three ways that microbes cause damage to hosts
-By secreting proteins (enzymes or toxins) that directly damage host cells
-By causing an overreaction by the body’s defenses and those defenses cause host damage
-By altering the host cell genome or transcription processes through epigenetic changes that temporarily or permanently disrupt normal host cell function.
What is a toxin
a chemical product of the one organism that is poisonous to another
What is a endotoxin?
A toxin molecule secreted by a living bacterial cell into the infected tissues
What is a exotoxin?
A toxin that is not actively secreted but is shed from the outer membrane
What is systemic infection?
which the pathogen spreads through circulation to many sites
What is locialized infection?
the microbe enters the body and remains confined to a specific tissue
What is secondary infection?
In a primary-secondary infection, an initial infection is complicated by a second one in the same or a different location and caused by a different microbe.
What is a focal infection?
occurs initially as a local infection, but circumstances cause the microbe to be carried to other sites systemically
What is a mixed infection?
which the same site is infected with several microbes at the same time
What is a acute disease or acute infections?
develops quickly and over quickly
What is a chronic disease or chronic infections?
develops more slowly, and lasts longer or indefinitely
What is the fifth step of an infection?
vacating the Host: portals of exit
What are ways of portals of exit?
skin cells, coughing, insect bites, removal of blood, feces, urine
What are the stages of Disease?
incubation period, prodrdomal stage, acute phase, convalescent period, continuation stage
What is a reservoir?
the primary habitat in the natural world from which a pathogen originates or when pathogens persist
Examples of reservoirs
human carrier, animal (vector), and non-living
What are carriers?
a person that is not affected by disease but can pass it on without knowning.
Asymptomatic carriers are what?
people who are infected but don’t have symptoms
incubating carriers are what?
people who are infected but don’t have symptoms
convalescent carriers are what?
when they continue to shed viable microbes and convey the infection to others
chronic carriers are what?
An individual who shelters the infectious agent for a long period after recovery because of the latency of the infectious agent
passive carriers are what?
Medical and dental personnel who must constantly handle materials that are heavily contaminated with patient secretions and blood risk picking up pathogens mechanically
what is zoonosis?
diseases that can be passed from animals to humans
What are biological vectors?
are infected
What are mechanical vectors?
not infected
Examples of biological vectors?
chickens, bats, mosquitoes
Examples of mechanical vectors?
flys and cockroaches
What are examples of non-liing reservoirs?
-soil
-water
-air
-improperly stored food
-buildings
What is communicable disease?
spreads from host to another
What is a noncommunicable disease?
infectious disease does not arise through transmission of the infectious agent from host to host.
What is contagious disease?
infectious disease spreads easily (opprotunistic infections)
What is Direct (contact) transmission?
Invovlves very close proxmity or actual physical contact between two hosts
What is an indirect transmission?
Infectious agents must pass from an infected host to an intermediate conveyor (a vehicle) and from there to another host. (example: touching a door knob, soil, water)
What is airborne transmission?
-moving through the air without dropping to the group
-Can stay in the air for long periods of time
What is a droplet transmission?
occurs by the direct spray of large droplets onto conjunctiva or mucous membranes of a susceptible host when an infected patient sneezes, talks, or coughs
