Chapter 14 Flashcards
Principles of Disease and Epidemiology
Pathology
Scientific study of disease, concerning the cause of disease and the structural and functional changes brought about by disease and with their final effects on the body
Etiology
The study of the cause of disease
Pathogenesis
The manner in which disease develops
Infection
The invasion or colonization of the body by pathogenic microorganisms pr the presence of a microorganism in part of the body where it is not normally found. It can exist in the absence of detectable disease; no symptoms.
Disease
Occurs when an infection results in any change from a state of health. It’s an abnormal state. The body cannot perform all it’s normal functions. Part or all of the body is not properly adjusted.
Human Microbiome Project
Began in 2007 to analyze microbial communities called microbiomes that live on and in the body. With a goal of trying to determine the relationship between changes in human microbiome and human health and disease.
Normal microbiota
Normal flora; Microorganisms that establish more or less permanent residents (colonize) but do not produce disease under normal conditions.
Transient microbiota
Microorganisms that may be present for several days, weeks, or months and then disappear. They are not found throughout the entire human body but are localized in certain regions.
What are the factors that determine the distribution and composition of normal microbiota
Nutrients, physical and chemical factors, defenses of the host, and mechanical factors.
How do nutrients affect normal microbiota and where do they come from
Microbes can colonize only those body sites that can supply the appropriate nutrients. These nutrients maybe derived from secretory and excretory products of cells, substances in body fluids, dead cells, and foods in the gastrointestinal tract.
What are the physical and chemical factors that affect the growth of microbes and result in normal microbiota
Temperature, pH, available oxygen and carbon dioxide, salinity, and sunlight
What are mechanical forces that the human body uses against microbes
Mechanical forces such as chewing, the flow of saliva and digestive secretions, the flushing of urine during urination.
How does the human body’s protect itself against microbes
The human body has a variety of molecules and activated cells that kill microbes, inhibit their growth, prevent their adhesion to host cell surfaces and neutralize toxins that microbes produce.
Microbial antagonism
Also known as competitive exclusion. A manner in which normal microbiota can benefit the host by preventing the overgrowth of harmful micro organisms, involving competition among microbes.
How does microbial antagonism protect the host against colonization by potentially pathogenic microbes
Normal microbiota compete with pathogenic microbes for nutrients and they produce substances harmful to the invading microbes and affect conditions such as pH and available oxygen.
What is the relationship between the normal micro biota and the host called and what does it mean
Symbiosis. At least one organism is dependent on the other
Commenalism
Symbiotic relationship in which one of the organisms benefits and the other is unaffected
Mutualism
A type of symbiosis that benefits both organisms
Parasitism
A type of symbiosis where one organism benefits by deriving nutrients at the expense of the other.
How can a mutualistic organism become harmful? What’s an example
As long as it remains in it’s normal environment it is not infectious. Once it gets access to bbn other body sites it can become infectious. Example: E. coli in the large intestine is normal, if it gets into the urinary tract it can become infectious
Opportunistic pathogens
Microbes that do not ordinarily cause disease in their normal habitat in a healthy person but may do so in a different environment. Example: E. coli
Example of commensalism
Staphylococcus epidermidis on the skin
Example of mutualism, how
E coli in the large intestine. They synthesize Vit K and some B vit that are absorbed into the bloodstream and used by cells in the body. In exchange the large intestine provides nutrients used by baceria that allows for their survival
Other than competition among microbes, what is another factor in the cause of disease
Cooperation among microbes. Example: pathogens that cause periodontal disease and gingivitis have been found to have receptors, not for teeth, but for oral streptococci that colonize the teeth
Noninfectious diseases
Diseases that are not caused by microorganisms, such as inherited and degenerative diseases
Infectious diseases
Disease caused by microorganisms
Where is a key criterion in the validity of any scientific proof
That the experimental results be repeatable
In summary, what are Koch’s postulates
- The same pathogen must be present in every case of the disease
- The pathogen must be isolated from the diseased host and grown in pure culture
- The pathogen from the pure culture must cause a disease when it is inoculated into a healthy susceptible laboratory animal
- The pathogen must be isolated from the inoculated animal and it must be shown to be the original organism
What are some exceptions to Koch’s postulates
They are modified to establish etiologies of diseases caused by viruses and some bacteria which cannot be grown on artificial media
What are some diseases that cannot be verified by Koch’s postulates
▪︎Tetanus have unequivocal signs and symptoms
▪︎Pneumonia and nephritis may be caused by a variety of microbes
▪︎Certain pathogens, such as HIV, cause disease in humans only
▪︎Some pathogens, such as S. pyrogenes, cause several different diseases
Symptoms
Subjective changes in body function such as pain and malaise
Signs
Objective changes that can be observed and measured such as swelling, fever, and paralysis
Syndrome
A specific group of symptoms and signs that accompany a particular disease
Communicable disease
Any disease that spreads from one host to another, either directly or in directly
Examples of communicable diseases
Chicken pox, measles, general herpes, typhoid fever, tuberculosis
Contagious diseases
Diseases that are easily spread from one person to another
Examples of contagious diseases
Chicken pox and measles
Non communicable disease
Diseases caused by microorganisms that normally inhabit the body and only occasionly produce disease, and is not spread from one person to another. Some only cause disease when they reside on the body and somehow get inside the body.
Incidence
The number of people in a population who develop a disease during a particular time period
Prevalence
The number of people in a population who develop a disease at a specified time regardless of when it 1st appeared. This includes both old and new cases.
What is a good indicator of the spread of disease
Incidence
Sporadic disease
A disease that occurs only occasion only
Endemic disease
A disease constantly present in a population
Epidemic disease
A disease acquired in a given area in a relatively short period
Pandemic
A disease occurring in the world wide
Acute disease
A disease that develops rapidly but lasts only a short period of time
Chronic disease
A disease that develop slowly and the body’s reaction May be less severe but the disease is likely to continue to recur for long periods
Sub acute disease
A disease that it is intermediate between acute and chronic
Latent disease
A disease in which a causative agent remains inactive for a time but then becomes active and produces symptoms of the disease
Herd immunity
When many Immune people are present in a community
Local infection
An infection in which the invading micro organisms are limited to a relatively small area of the body
Example of local infection
Boils and abscesses