Ch14Notes - Chapter 14-Principles of Disease and...

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I. Pathology, Infection, and Disease. a. Pathology: Scientific study of disease. b. Etiology: Study of the cause of a disease. c. Pathogenesis: Development of a disease. d. Infection: Colonization of the body by pathogens, or the presence of a microbe in a part of the body where it is not normally found. e. Disease: An abnormal state in which the body is not functioning normally. II. Normal Microbiota. Fig. 14.2. a. Permanently colonize the host. i. The human body is made up of 1 x 10 13 cells (10,000,000,000,000 = 10 trillion) but it also contains 1 x 10 14 bacteria (100,000,000,000,000 = 100 trillion). b. Normal microbiota are only found in certain regions of the body. c. Transient microbiota may be present for days, weeks, or months. d. Relationships Between the Normal Microbiota and the Host. i. Microbial antagonism is competition between microbes. 1. Normal microbiota prevent harmful microorganisms from overgrowing in the following ways: a. Occupying niches that pathogens might occupy. b. Producing acids. c. Producing bacteriocins (compounds that kill other bacteria). 2. Probiotics are live microbes applied to or ingested into the body, intended to exert a beneficial effect. ii. Symbiosis is the relationship between a microbe and its host. 1. In commensalism, one organism is benefited and the other is unaffected. a. Many of the normal microbiota are commensals. 2. In mutualism, both organisms benefit. a. Many of the normal microbiota are mutualists. 3. In parasitism, one organism is benefited at the expense of the other. a. Many disease causing organisms are parasites. e. Opportunistic Microorganisms. i. Some normal microbiota are opportunistic pathogens. 1. They normally do not cause disease in healthy individuals. 2. They can cause disease if they colonize an area where they are not normally found. 3. Individuals with compromised immune systems often become infected with opportunistic pathogens. III. The Etiology of Infectious Diseases. a. Koch’s Postulates. Fig. 14.3. i. Used to prove the cause of an infectious disease. 1. The same pathogen must be present in every case of the disease. 2. The pathogen must be isolated from the diseased host and grown in pure culture. 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism. b. Exceptions to Koch’s Postulates. i. Some microorganisms have unique culture requirements and cannot be cultured on artificial media. ii.
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This note was uploaded on 11/05/2010 for the course BIOL 211 taught by Professor Paxton during the Fall '10 term at Salem College.

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Ch14Notes - Chapter 14-Principles of Disease and...

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