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UNIT 3Module 9Ch16,19: HostMicrobe Interactions and EpidemiologyCh16: HostMicrobe Interactions●Compare and contrast mutualism, commensalism, and parasitism.○symbiosis→the intimate relationships between the microorganisms and humanbody that “live together”○mutualism→symbiotic association in which both partners benefit (i.e bacteria inlarge intestine)○commensalism→symbiotic association in which one partner benefits and theother remains unharmed (i.e microbes living on skin)○parasitism→symbiotic association in which the parasite benefits and the host isharmed. All pathogens are parasites (i.e protozoa, helminths).●Describe three protective roles of the normal microbiota.○Normal microbiota(normal flora) → organisms that routinely reside on body’ssurfaces and do not cause disease. Its composition is dynamic. Plays aprotective role by:■covering binding sites that might otherwise be used for attachment■consuming available nutrients■producing compounds toxic to other bacteria■simulation of adaptive immune system■important in the development of oral tolerance●Describe how the composition of the normal microbiota can change over time.○Changes can occur over time in response to physiological variations within thehost and as a direct result of the activities of the human host.○Resident microbes→pathogens that inhabit sites for extended periods and canchange over time1
UNIT 3Module 9Ch16,19: HostMicrobe Interactions and Epidemiology○Transient microbes→pathogens that temporarily inhabit a specific site. Mostare harmless but some are pathogens. Important to human health.○Opportunistic microbes→pathogens that cause disease given the opportunity●Define terms of pathogenicity○primary pathogen→a microbe or virus that is able to cause disease inotherwise a healthy individual○opportunistic pathogen→organism that causes diseases only when the body’sinnate or adaptive defenses are compromised or when introduced into anunusual location○virulence→ability of a pathogen to cause disease○virulence factors→microbial components that contribute to the ability to causedisease in a susceptible host. Increase the ability of a pathogen to cause diseaseby allowing pathogen t adhere to or penetrate host cell, thwart immune defenseand damage host●Describe the characteristics of infectious diseases.○colonization→multiplication of microorganisms without necessarily resulting intissue invasion or damage○infection→colonization of a host by a microorganisms with or without disease○communicable diseases→infectious diseases that spread from one host toanother (i.e measles, colds)○infection dose→the number of microbes necessary to establish infection■ID50→ experimentally derived figure that indicates the number of cells thatinfects 50% of population●Describe the course of disease○Incubation period→