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three types of symbiosis


organisms that live in and on the body

normal micobiota

both members benefit


when a parasite benefits whie the host is harmed


when one member benefits while the other is relatively unaffected


the womb is an ___________, meaning free of microbes

axenic environment

the process by which pathogens attach to cells


study of the cause of a disease


Kochs postulates

1. suspect pathogen must be present in every case of the disease
2.pathogen must be isolated and grown in pure culture
3. cultured pathogen must cause the disease when introduced into a healthy host
4. same pathogen must be reisolated from the diseased host

the ability of a microorganism to cause a disease


the degree of pathogenicity is called


Endotoxin is also know as _______as is gram negative

Lipid A

the spread of pathogens via air, drinking water, and food as well as bodily fluids being handled outside the body

vehicle transmission

this involves the spread of pathogens to teh respiratory mucous membranes of a new host via an aerosol

airborne transmission

Vectors that not only transmit pathogens but also serve as hosts for the multiplication of a pathogen during some stage of its life cycle

Biological vector

Vectors that are not required as hosts by the pathogens they transmit;such vectors only passively carry pathogens on their feet or other body parts

mechanical vectors

The study of the location, course, and transmission of diseases within population


three types of reservoirs

animal, human, nonliving

The mere presence of microbes in or on the body


when the organism evades bodys external defenses, multiplies and becomes established in the body


Four major pathways for portals of entry

skin, mucous membrane, pacenta, parenteral route

virulence factors that contribute to virulence

adhesion, biofilms, extracellular enzymes, toxins, antiphagocytic factors.

collangenase and hyaluronase

breaks down collagen


helps foreign object to enter blood stream


disolves cell membrane

Exotoxins classifications by locations


Exotoxins classifications by structure & function

A-B toxin
membrane disruption
super antigens

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