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47 Cards in this Set

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  • Back
What are microorganisms usually found associated with human body tissue?
Normal microbial flora
What cause disease either by infection, intoxication, or allergy?
Pathogens
What is the ability to cause damage or disease?
Pathogenicity
What is the quantitative measure of pathogenicity?
Virulence
What causes disease only in the absense of normal host resistance?
Opportunistic pathogen
What is the situation in which a microbe is established and growing in a host, whether or not the host is harmed?
Infection
What is dmaage or injury to the host that impairs host function?
disease
At what site do infections normally begin at?
mucous membranes
The composition of normal flora on the skin is influenced by what factors?
environmental factors such as weather and host factors such as age and personal hygeine.
Most normal flora on skin are composed of what types of cells?
G+
Saliva contains what type of enzymes?
antimicrobial enzymes
Bacteria colonize tooth surfaces by first attaching to acidic _______ deposited there by saliva.
glycoproteins
Extensive growth of oral microorganisms, especially streptococci, results in a thick bacterial layer know as?
dental plaque
As plaque continues to develop on a tooth, ______ bacterial species begin to grow.
anaerobic
As dental plaque accumulates, the microorganisms produce high concentrations of acid that results in decalcification of the tooth enamel known as?
dental caries
The lactic acid bacteria _______ and ________ mutans are common agents in dental caries.
Streptococcus sobrinus and streptococcus mutans
Microbial populations in the GI tract are influenced by what?
diet and the physical conditions in that area
What prevents many organisms from colonizing in the GI tract?
The acidity of the stomach and the duodenum(1st part) of the small intestine (pH=2)
Intestinal microorganisms carry out a variety of essential metabolic reactions that produce various compounds such as?
-vitamins
-gas, organic acids, odor
-enzymes
A restricted group of organisms colonizes the upper respiratory tract. Give some examples.
staphylococci, streptococci, diphtheroid bacilli, and G- cocci.
The _____ respiratory tract lacks microflora in healthy individuals.
lower
What two microorganisms usually cause UTIs in women?
E. coli and P. mirabilis
The vagina of the adult female is weakly acidic and contains significant amounts of _____.
glycogen
What organism ferments glycogen in the vagina producing lactic acid?
Lactobacillus acidophilus
What is the relative ability of a pathogen to cause a disease?
Virulence
How is virulence measured?
By experimental studies of the LD50(lethal dose 50) which is the amount of an agent that kills 50% of the animals in a test group
What would be an example of a highly virulent organism?
Streptococcus pneumoniae
What is the decrease or loss of virulence?
Attenuation
What is it called when an organism causes disease by means of a toxin that inhibits host cell funtion or kills host cells?
Toxicity
What is the ability of a pathogen to grow in host tissue at densities that inhibit host function(can cause damage without producing a toxin)?
Invasiveness
Pathogen invasion starts at the site of adherence and may spread throughout the host via the ________ or _______ systems.
circulatory or lymphatic
What is it called when a pathogen must gain access to host tissues and multiply before damage can be done?
specific adherence
Bacterial adherence can be facilitated by what?
-extracellular macromolecules that are not covalently attched to the bacterial cell surface(slime layer, capsule)
-fimbriae and pili
What is most important in affecting pathogen growth?
the availability of nutrients
Pathogens produce enzymes that enhance virulence by breaking down or altering host tissue to provide access to nutrients. What would be an example of this type of enzyme?
hyaluronidase
Pathogens also produce enzymes that protect the pathogen by interfering with normal host defense mechanisms. An example of this enzyme would be?
coagulase
What are proteins released from the pathogen as it grows?
Exotoxins
What are three categories of exotoxins?
cytolytic toxins, AB toxins, and superantigen toxins
How do cytolytic toxins work?
Toxins thatlyse red blood cells are called what?
- by degrading cytoplasmic membrane integrity, causing cell lysis and death.
- hemolysins
How to AB toxins work? What are some examples?
- By binding to host cell receptor( B subunit) and transferring damaging agent (A subunit) across the cell membrane.
- diptheria toxin, tetanus toxin, and botulinum toxin
What two organisms produce potent AB exotoxins that affect the nervous system?
Clostridium tetani and Clostridium botulinum
What is a type of exotoxin whose activity affects the small intestine and generally cause massive secretions of fluid into the intestinal lumen causing vomiting and diarrhea? List an example
Enterotoxins (cholera toxin)
What type of toxin consists of the lipopolysaccharide portion of the cell envelope of certain G- bacteria? (toxic when solubilized)
Endotoxins
The prescence of endotoxins can be detected by what?
the Limulus amoebocyte lysate(LAL) assay.
What is a host called that consist of one or more inactive resistance mechanisms and has an increased probability of infection?
Compromised host
What are some common risk factors that canlead to compromised host?
-Age(very young or very old)
-Stress
-Diet
-Certain genetic conditions
What are some reasons as to why hosts have an innate resistance to most pathogens?
-natural host resistance
-tissue specificity
-physical and chemical barriers