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67 Cards in this Set

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  • Back
"to live together"
3 types of symbiotic relationships and their defenition
Mutualism- Both benefit from the relationship
Commenalism- One benefits and the other is indifferent to the relationship
Parasetism- one benefits and the other is harmed by the relationship
Refers to the organisms that colonize the body's surfaces WITHOUT normally causing disease
NORMAL mirobiota (or flora)
two types of Normal microbiota include
Resident microbiota and Transient microbiota
Resident microbiota
Are part of the normal microbiota throughout life (most are commensal- 1 benefit 1 indifferent)
Teansient microbiota
Remain in the body for only hours to months (cannot persist on the body because of bodys defense and competition)
Acquisiton of Normal Microbiota
Most begins to develop during the BIRTHING PROCESS and in the coming months.
Oppurtunistic pathogens (what makes normal microbiota cause disease?)
All of the following
-Immunosuppresion (comprimised hosts)
- changes in relative abundance
- introduction to an unusual site on the body.

Every orifice in the body contains micoroganisms.
Contamination vs infection
Contamination- the mere prescence of microbes.

Infection when the organism that has contaiminated can MULTIPLY and become established.
4 main portals of entry
-Mucous Membranes
-Parenteral route
How pathogens pass the 1st portal of entry (skin)...
Some can pass through openings or cuts and some can burrow beneath the skin and sweat glands.
Portal of entry- Mucous Membrane
Lines all orifice to the body. Many pathogens can also survive the pH of the stomach.
The most common site of entry for pathogens
Respiratory tract (Mucous membrane)
Portals of entry- Parenteral route
Not a true portal of entry. Pathogens deposited into tissues BENEATH THE SKIN or mucous membrane.
process by which microorganisms attach themselves to cells
What are the specialized structures that allow ADHESION
Pilli, Fimbrae and Capsule.
Attachment proteins in microbes

-block ligands and the microbe becomes avirulent.
Attachment proteins (ligands) give rise to what
the specificity of host cell target for the microbe to bind to.
Infection vs Disease
Infection- the INVASION of a host by a pathogen.

Disease- results only if the invading pathogen ALTERS THE NORMAL FUNCTIONS of the host.
Symptom, Sign or syndrome

subjective characteristics of disrase FELT ONLY BY THE PATIENT.
Symptom, Sign or syndrome

objective manifestations of disease that can be OBSERVED BY OTHERS
Symptom, Sign or syndrome

group of symptoms and signs that characterize a disease or abnormal condition
What does it mean to be asymptomatic?
LACKING SYMPTOMS, however, infection MAY still be present.
study of the causes of diseases
Koch's Postulates (5 stages)
Reproduce infection
Exceptions to disease classifications through Koch's Postulate
- Some pathogens cant be cultured
- some disease caused by multiple pathogen
-Ethical considerations
Pathogenicity vs Virulence

ABILITY of a microbe to cause disease
Pathogenicity vs Virulence

degree to which a microbe causes disease
4 factors affecting virulence
- Extracellular enzymes
- Adhesion factors
- Toxins
-Antiphygocytic factors
Extracellular enzymes and their effect on virulence
-enzymes secreted by the pathogen.
-dissolve structural chemicals in the body
-help pathogens mantain infection, and avoid body defenses
Toxins and their effect on Virulence
-Toxins are chemicals that are produced by the pathogen.
-Cause harm to tissues (actively or passively)
toxins in the bloodstram that are carriend beyond the site of infection
2 classes of toxins
Endotoxin- part of the structure of gram negative bacteria (such as LPS)

Exotoxin- proteins that are both produced and excreted by the pathogen
Recall there are 2 classes of toxins (endo and exotoxins). There are also 2 types of EXOTOXINS called....
Neurotoxins- Botulism and Tetanus

Enterotoxin- Staph and Cholera
Virulence effects of Antiphygocytic factors
Capsules- either infect cell without being recognized as foreign or are "slippery" and avoid phagocytosis.

-Antiphagocytic chemicals- prevent fusion of lysosomes (TB) and kill luekocytes.

*Lysosome function
*Capsule makes more/less virulent
*what organism avoids fusion with lysosomes? consequence?
- Lysosomes- lyse the cell rendering it dead.
- TB; highly virulent
Three stages of infectious diseases
-Incubation (no symptoms)
-Illness (most sever symptom)
-Convalescence (no symptoms)
How pathogens leave host?
- GI Tract- feces
- respiratory- sneezing
- Gential- secretions and urine
Sites where pathogens are mantained as a source of infection
3 types of reservoirs
-Animal reservoir
- Human carrier
- Nonliving reservoir
diseases that are naturally spread from their usual animal host to humans
Ways Zoonoses are transfered
-direct contact with feces or carier
-eating animals
-bloodsucking arthropids (mosquitos)
In zoonotic humans are usually
the dead end host.
infected individuals who are asymptomatic but infective to others
human carriers
What is an example of a human carrier?
The gall bladder stores the pathogen causing typhoid fever causing infection in many people
Non living reservoirs
Soil, water and food can all be reservoirs for infection. (usually due to contamination with urine or feces)
Modes of transmission (3 methods)
- Contact transmission- direct contact
-Vehicular transmission- Food, H20, air
-Vector transmission- Mosquito
Droplets causing cold are what type of mode of transmission
the study of where and when diseases occur and how they are transmitted within populations
number of NEW cases of a dusease in a given area in a given time
Incidence (different from prevalence)
number of TOTAL cases of a disease in a given area in a given time
Prevalence (different from incidence)
the 3 approaches to epidemiology
Descriptive- how did it get started
Analytical- how to stop transmission
Experimental- application of Koch's Postulats
the main purpose of descriptive epidemiology is
to identify INDEX CASES (the 1st case of the disease)
The purpose of analytical epidemiology?
seeks to solve "mode of transmission" amd medthods of prevention. often RETROSPECTIVE (after the fact)
Purpose od experimental epidemiology?
Testing of hypothesis in descriptive and analytical epidemiology.
Infections acquired while in helath care faciities
Noscomial Infections
The most common nosocomial indectious agent are from the genus...
Control of Noscomial infections

-What helps most?
-Who mandates controls in this field?
-Handwashing to reduce disease

- the CDC has universal percautions to limit exposure to pathogens
The CDC's job in the U.S is accomplished by ___________ internationally.
WHO- World Health Organization
Immune system can be broken down into 2 SYSTEMS
Innate (Non-specific) and Acquired (Specific)
Within Innate there are 2 line of defense against pathogens they are:
1st line of defense- Physical barrier- (Skin, Secretions and Normal flora)

2nd line of defense- Blood components (Phagocytic cells, compliment fever and inflammation)
The Acquired or Specific system (3rd line of defense) of immunity further breaks into two categories what are they...
1. Humoral (B cells and Antibodies (A and B))

2. Cell mediated immunity- (Tc- Killer T cells and Th Helper T cells)
What is the major difference between the two classes of Acquired or Specific immunity (Humoral vs Cell-mediated)
Humoral system guards against extracellular problems.

Cell mediated immunity corrects intracellular pathogens (including cancerous cells) and VIRUSES!
Nonspecific immunity includes complement system which secretes...
proteins (perforin) hich kill cells by cytolysis
Nonspecific immunity contains the inflammatory response which causes the following four SIGNS and SYMPTOMS.
Signs: redness, heat and swelling

Symptoms: Pain
What is the purpose of the inflammatory response?
to get the necessary defense systems to the site of injury quicker because of vasodilation.

1.) destroys infectious agent
2.) localizes damage to external tissue.
3.) replaces or repairs damaged tissue