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61 Cards in this Set
- Front
- Back
Pathogens
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Disease- causing microorganisms.
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Pathogenic Microorganisms
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have special properties that allow them to invade the human body or produce toxins.
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A state of Disease Results...
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after a microorganism overcomes the body's defenses.
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Pathology
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is the scientific study of disease.
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Pathology is concerned...
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with the Etiology (cause), Pathogenesis (development), and Effects of disease.
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Infection
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is the invasion and growth of pathogens in the body.
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Host
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is an organism that shelters and supports the growth of pathogens.
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Disease
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is an abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions (loss of Homeostasis).
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who are germ free in utero?
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Animals, including humans then to be.
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When do microorganisms begin colonization in and on the surface of the body?
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Soon after birth.
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What makes up the Normal Microbiota (normal flora)?
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microorganisms that establish Permanent colonies inside or on the body without producing disease.
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Transient microbiota
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are microbes that are present for various periods and then disappear.
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The phenomenon where the normal microbiota can prevent pathogens from causing an infection is known as?
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Microbial antagonism.
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Normal microbiota and the....
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host exist in symbiosis (living together).
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What type of Symbiosis has one organism that benefits and the other is unaffected?
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Commensalism
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What type of Symbiosis has both organisms benefiting?
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Mutualism
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What type of Symbiosis has one organism benefiting and the other is harmed?
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Parasitism
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What pathogens do not cause disease under normal conditions but cause disease under special conditions?
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Opportunistic Pathogens
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Koch's Postulates
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are criteria for establishing that specific microbes cause specific diseases.
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What are the requirements for Koch's Postulates:
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- The same pathogen must be present in every case of the disease.
-The pathogen must be isolated in pure culture. -The pathogen isolated from pure culture must cause disease in a healthy, susceptible laboratory animal. -The pathogen must be re-isolated from the inoculated laboratory animal. |
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Exceptions to Koch's Postulates:
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-Koch's postulates are modified to Establish Etiologies of diseases caused by viruses and some bacteria which cannot be grown on artificial media.
-Some diseases, such as tetanus, have unequivocal signs and symptoms. -Some diseases, such as pheumonia nad nephritis, may be caused by a variety of microbes. -Some pathogens, such as S. pyogenes, cause several different diseases. -Certain pathogens, such as HIV, cause disease in humans only. |
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Symptoms
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Subjective changes in body functions
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Signs
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measurable changes
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Syndrome
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a specific group of symptoms or signs that always accompanies a specific disease.
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Communicable diseases
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are transmitted directly or indirectly from one host to another.
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Contagious disease
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is one that is easily spread from one person to another.
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Non-communicable diseases
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are caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another.
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Disease occurance is reported by.....
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incidence and prevalence.
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Incidence-
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number of people contracting the disease in a given time period.
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Prevalence-
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number of total cases at a particular time regardless of when they developed.
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Sporadic
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occurs occasionally (typhoid fever in the us).
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Endemic
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constantly present in a population (common cold).
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Epidemic
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many cases in a given area in a short period of time (influenza).
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Pandemic
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a world wide epidemic (influenza occasionally, AIDS might be considered pandemic).
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Acute-
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develops rapidly but lasts a short time (influenza).
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Chronic-
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develops more slowly, reactions to the disease are less severe, likely to be continual or recurrent for long periods (infectious mononucleosis, TB, hepatitis B).
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Subacute-
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intermediate between acute and chronic (sclerosing panencephalitis- a progressive/slow viral disease).
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Latent-
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the causative agent remains inactive for a time but then becomes active to produce symptoms (shingles).
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Herd Immunity
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is the presence of immunity to a disease in most of the population.
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Local infection
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affects a small area of the body.
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Systemic infection
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is spread throughout the body via the circulatory system.
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Secondary infection
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can occur after the host is weakened from a primary infection.
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Inapparent or Subclinical Infection
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does not cause any signs of disease in the host.
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Predisposing factor
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is one that makes the body more susceptible to disease or alters the course of a disease. (ex. gender, climate, age, fatigue, and inadequate nutrition.)
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Incubation period
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the time interval between the initial infection and the first appearance of signs and symptoms.
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Prodromal period
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characterized by the appearance of the first mild signs and symptoms.
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Period of illness
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the disease is at its height, and all disease signs and symptoms are apparent.
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Period of illness:
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-Death may occur during the period of illness
-Crisis is the phase of fever characterized by vasodilation and sweating (the body is trying to return to normal temperature, the fever is breaking). |
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Period of decline
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the signs and symptoms subside.
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Period of convalescence
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the body returns to its prediseased state, and health is restored.
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Reservoir of infection
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a continual source of infection.
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Human reservoirs of infection: (living reservoirs)
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-People who have a disease.
-People who are carriers of pathogenic microorganisms. |
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Zoonoses (living reservoirs)
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are diseases that affect wild and domestic animals and can be transmitted to humans.
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Nonliving Reservoirs:
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-Soil (fungi, C. botulinum, C. tetani)
-Water (V. cholerae, S. typhi, protozoans, algae) -Improperly prepared or stored foods (trichinosis and salmonellosis). |
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Direct contact (contact transmission)
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(person-to-person) involves close physical contact between the source of the disease and a susceptible host.
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Indirect contact (contact transmission)
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involves transmission by fomites (inanimate objects).
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Droplet transmission (contact transmission)
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is transmission via droplet nuclei (mucus droplets) in coughing or sneezing, laughing or
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Common Vehicle transmission-
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is transmission by a medium such as water, food or air.
-Waterborne -Foodborne -Airborne- pathogens are carried on droplet nuclei in dust for a distance greater than 1 meter. |
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Arthropod vectors (vector transmission)
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carry pathogens from one host to another by both mechanical and biological transmission.
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Mechanical transmission (vector transmission)
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is the passive transport of a pathogen on a vector's feet or other body parts.
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Biological transmission (vector transmission)
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involves reproduction of the pathogen in the vector and transmission in saliva or feces.
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