UNIT 3-Module 9-Ch16,19_ Host-Microbe Interactions and Epidemiology.pdf

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UNIT 3­Module 9­Ch16,19: Host­Microbe Interactions and Epidemiology Ch16: Host­Microbe Interactions Compare and contrast mutualism, commensalism, and parasitism. symbiosis→ the intimate relationships between the microorganisms and human body that “live together” mutualism→ symbiotic association in which both partners benefit (i.e bacteria in large intestine) commensalism→ symbiotic association in which one partner benefits and the other remains unharmed (i.e microbes living on skin) parasitism→ symbiotic association in which the parasite benefits and the host is harmed. 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’s surfaces and do not cause disease. Its composition is dynamic. Plays a protective 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 the host and as a direct result of the activities of the human host. Resident microbes→ pathogens that inhabit sites for extended periods and can change over time 1
UNIT 3­Module 9­Ch16,19: Host­Microbe Interactions and Epidemiology Transient microbes→ pathogens that temporarily inhabit a specific site. Most are 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 in otherwise a healthy individual opportunistic pathogen→ organism that causes diseases only when the body’s innate or adaptive defenses are compromised or when introduced into an unusual location virulence→ ability of a pathogen to cause disease virulence factors→ microbial components that contribute to the ability to cause disease in a susceptible host. Increase the ability of a pathogen to cause disease by allowing pathogen t adhere to or penetrate host cell, thwart immune defense and damage host Describe the characteristics of infectious diseases. colonization→ multiplication of microorganisms without necessarily resulting in tissue invasion or damage infection→ colonization of a host by a microorganisms with or without disease communicable diseases→ infectious diseases that spread from one host to another (i.e measles, colds) infection dose→ the number of microbes necessary to establish infection ID 50 → experimentally derived figure that indicates the number of cells that infects 50% of population Describe the course of disease Incubation period→

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