Textbook material Flashcards
What does it mean that microbes are ubiquitous?
They are found in all natural habitats and most of those that have been created by humans
What is microbiology?
A specialized area of biology
- deals with microscopic organisms
What are the major groups of microorganisms included in microbiology?
- Bacteria
- Viruses
- Fungi
- Protozoa
- Algae
- Helminths
What defines prokaryotes?
Genetic material is not bound by membranes
- lack nucleus and organelles
- still contain genetic material
What defines eukaryotes?
Contain a “true” nucleus
- membrane bound organelles
What is bacteriology?
Study of bacteria
- small, single-celled prokaryotic organisms
What is mycology?
Study of fungi
- group of eukaryotes that includes both microscopic eukaryotes (molds and yeasts) and larger organisms (mushrooms)
What is protozoology?
Study of protozoa
- animal-like, mostly single-celled eukaryotes
What is virology?
Study of viruses
- minute, noncellular particles that parasitize cells
What is phycology (algology)?
Simple photosynthetic eukaryotes (algae)
- ranging from single celled to large seaweeds
What is genetic engineering?
A newer area of biotechnology that manipulates the genetics of microbes, plants, and animals
- purpose of creating new products and genetically modified organisms
What is recombinant DNA?
Powerful technique for designing new organisms
Where does a parasite live? Where does it get it’s sustenance?
Lives in or on the body of a larger organism and derives its sustenance from the host
What is deductive reasoning?
Deduction of facts that can account for what has been seen
What is a theory?
A collection of statements, propositions, or concepts that explains or accounts for a natural event
- an entire body of ideas that expresses or explain many aspects of a phenomenon
When does a theory become a law?
When the evidence of the accuracy and predictability of a theory is so compelling - it becomes law
What does sterile mean?
Completely free of all life forms including spores and viruses
What did Dr. Oliver Wendell Holmes demonstrate?
Mothers who gave birth at home experienced fewer infections than did mothers that gave birth in the hospital
What did Dr. Ignaz Semmelwels show?
Women became infected in the maternity ward after examinations by physicians coming directly from the autopsy room
What did the surgeon Joseph Lister introduce?
Aseptic techniques
- aimed at reducing microbes in a medical setting and preventing wound infections
What is taxonomy?
Formal system for organizing, classifying, and naming living things
Who invented taxonomy?
Carl Von Linne
What is classification?
An orderly arrangement of organisms into groups that indicate evolutionary relationships and history
What is identification?
Process of determining and recording the traits of organisms in order to trace their exact identity and placement in taxonomy
What is a hierarchy?
How the main taxa (or groups) in a classification scheme are organized
What is a domain?
A giant, all-inclusive category based on a unique cell type
What is the order of taxa, in descending order?
- Domain
- Kingdom
- Phylum (or division)
- Class
- Order
- Family
- Genus
- Species
What is the scientific name (specific epithet)
Combination of the generic (genus) name followed by the species name
- always italicized
- Generic part of the scientific name is capitalized, and the species part begins with a lowercase letter
What are the four distinct phases of infection and disease?
- Incubation period
- Prodromal stage
- Period of invasion
- Convalescent period
What is the incubation period?
Time from initial contact with the infectious agent (at the portal of entry) to the appearance of the first symptoms
What do the earliest notable symptoms of infection appear as?
Vague feelings of discomfort (head and muscle aches, fatigue, malaise)
What occurs during the prodromal stage?
Earliest notable symptoms
What happens during the period of invasion?
The infectious agent multiplies at high levels, exhibits its greatest toxicity, and becomes well established in its target tissues
What happens during the convalescent period?
Patient responds to the infection, symptoms decline
- or if the patient dies, the infection is considered terminal
What is a localized infection?
Microbe enters the body and remains confined to a specific tissue
What is a systemic infection?
When an infection spreads to several sites and tissue fluids, usually in the bloodstream
What is a focal infection?
Exists when the infectious agent breaks loose from a local infection and is seeded or disseminated into other tissues
What is a mixed infection?
When an infection is not caused by a single microbe
- several agents establish themselves simultaneously at the infection site
What is it called when an initial (primary) infection is complicated by another infection caused by a different microbe, what is it called?
Secondary infection
What are acute infections?
Infections that come on rapidly, with severe but short-lived effects
What are chronic infections?
Infections that progress and persist over a long period of time
What is a sign?
Any objective evidence of disease as noted by an observer
What is a symptom?
Subjective evidence of disease as sense by the patient
What are more precise, signs or symptoms?
Signs!
What is a syndrome?
When a disease can be identified or described by a defined collection of signs and symptoms
What is the name of the process that results from the activation of the body defenses, that shows the earliest symptoms of the disease?
Inflammation
What are some signs of inflammation?
- Edema (accumulation of fluid)
- Granulomas
- Abscesses
- Lymphadenitis (swollen lymph nodes)
What is leukocytosis?
Increase in the level of WBCs
What is leukopenia?
Decrease in the level of WBCs
What is septicemia?
Blood infection
- microorganisms are multiplying in the blood and are present in large numbers
What is bacteremia or viremia?
Small numbers of bacteria or viruses in the blood
- means they are present, but not necessarily multiplying
Define asymptomatic or subclinical.
Patient experiences no noticeable symptoms, even though the microbe is active in the host tissue
What is the portal of exit?
How pathogens depart by a specific avenue
What are some examples of how pathogens escape from the lower or upper respiratory tract?
- Coughing
- Sneezing
- Talking/laughing
- Mucus
- Sputum
- Nasal drainage
- Other moist secretions
What are some examples of portals of exits in epithelial cells?
Skin lesions and their exudates (warts, funcal infections, boilds, herpes, smallpox, syphilis)
What causes the increase in motility (speeding up peristalsis), which results in diarrhea?
Intestinal pathogens that grow in the intestinal mucosa and create inflammation
How can blood be a portal of exit?
When it is removed or released through a vascular puncture made by natural or artificial means
What is persistence or latency of microbes?
When the infectious agent retreats into the host
- the initial symptoms are gone
- not necessarily the disease
What is epidemiology?
Study of frequency and distribution of disease in defined populations
What is a vector?
A live animal that transmits an infectious agent from one host to another
What are some examples of vectors?
Fleas, mosquitoes, flies, ticks, birds
What is a biological vector?
Actively participates in a pathogen’s lifecycle
- serves as a site in which it multiplies or completes its life cycle
What is a mechanical vector?
Not necessary to the life cycle of an infectious agent and merely transports it w/out being infected
What is zoonosis?
An infection indigenous to animals but naturally transmissible to humans
What are normal resident microbiota?
Microbes that engages in mutual or commensal associations with humans
What results after a microbe has penetrated a host’s defenses, invades sterile tissues, and multiplied?
Infection!
What is the name for a microbe that is considered an infectious agent?
Pathogen
What is disease defined as?
Any deviation from heath
What is pathogenicity?
An organism’s potential to cause infection or disease
- used to divide pathogenic microbes into one or two general groups
What are true pathogens?
Primary pathogens that are capable of causing disease in health persons with normal immune defenses
When do opportunistic pathogens cause disease?
When the host’s defenses are compromised
- or when they become established in a part of the body that is not natural to them
What is virulence?
The degree of pathogenicity
- virulence of a microbe is determined by its ability to establish itself in the host and cause damage
Define portal of entry.
How a microbe enters the tissues of the body
- usually a cutaneous or membranous boundary
What is a very common portal of entry?
The Skin!
- nicks, abrasions, and punctures
What is the portal of entry for pathogens that are contained in food, drink, and other ingested substances?
Gastrointestinal tract
What are the portals of entry to the respiratory tract?
Oral and nasal cavities
What is the portal of entry for pathogens that are contracted by sexual means?
Urogenital tract
Where did the name Venereal disease, come from?
Victorian attitude that sex lead to diseases, from Venus (goddess of Love)
What is the exchange organ between mother and fetus?
The placenta
What is the function of the placenta?
- separates the blood of the mother from that of the fetus
- permits diffusion of dissolved nutrients and gases to the fetus
What is the infectious dose (ID)?
When the minimum number of microbes are present to cause infection
What is adhesion?
A process by which microbes gain a more stable foothold at the portal of entry
What is adhesion dependent on?
On the binding between specific molecules on both the host and pathogen
- a particular pathogen is limited to only those cells (and organisms) to which it can bind
What is a microbe’s virulence factor?
Properties that improve their invasiveness
- capacity to evade host defenses and enter deeper tissues
When a microbe encounters resistance from the host, where does the initial response come from?
Phagocytes
(white blood cells)
- these cells engulf pathogens and destroy them by means of enzymes and antimicrobial chemicals
What secretes exo-enzymes and and what do they do?
Pathogenic bacteria, fungi, protozoa, and worms secrete it
- disrupts the structure of tissues
What is a toxin?
A specific chemical product of microbes, plants, and some animals that have poisonous effects on other organisms
What is toxigenicity?
The power/ability to produce toxins
What is an exotoxin?
A toxin molecule secreted by a living bacterial cell into the infected tissues
What is an endotoxin?
A toxin that is not secreted but only released when the cell ruptures (is damaged or lysed)
What do hemolysins target?
Disrupts the cell membrane of RBCs - are a class of bacterial exotoxin
True or False:
There are many kinds of exotoxins and only one kind of endotoxin
True!
What is Lipopolysaccharide (LPS)?
Endotoxin
- part of the outer membrane of gram-negative cell envelopes
What is a reservoir?
Primary habitat in the natural world from which a pathogen originates
- human or animal carrier
- could be water, plants, or soil
What is a carrier?
An individual who INCONSPICUOUSLY shelters a pathogen and spreads it to others without any notice
When is a disease considered communicable?
When an infected host can transmit the infectious agent to another host and establish infection in that host
What does it mean when a disease is transferred horizontally?
Disease is spread through a population from one infected individual to another
What does it mean when a disease is transferred vertically?
Transmission is from parent to offspring
- via the ovum, sperm, placenta, or milk
