10-peranan-mikroba - 1 CATATAN KULIAH KE-14 PERANAN...

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CATATAN KULIAH KE-14 PERANAN MIKROORGANISME 31. Normal Microbiota and Nonspecific Host Resistance Chapter Overview This chapter focuses on the interactions of the human body with microorganisms. It begins by discussing the normal microbiota-those microorganisms that have established residence in or on the body. The relationship between humans and their normal microbiota is usually either mutualistic or commensal. On occasion, the interaction can shift to parasitism (a pathogenic relationship). In addition, microorganisms that are not part of the normal microbiota can be pathogenic. Humans resist parasitic relationships by employing both nonspecific and specific mechanisms. The nonspecific resistance mechanisms are explored in this chapter Chapter Objectives After reading this chapter you should be able to: describe gnotobiotic animals and their importance describe the body sites where normal microbiota are found and give examples of the microorganisms found there describe the cells, tissues, and organs of the immune system describe the physical and chemical barriers a pathogen must breach if a parasitic relationship is to be established describe inflammation and its role in providing nonspecific resistance describe the complement system and how it is activated describe how the complement system and phagocytosis function in inflammation and other nonspecific resistance mechanisms discuss cytokines and natural killer cells and their role in nonspecific resistance Study Outline Introduction Pathogenicity-the ability to produce pathological changes (disease) as the result of a parasitic symbiosis between a microorganism and a host Pathogen-any disease-producing microorganism 1
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Gnotobiotic Animals Gnotobiotic-an environment or animal in which all microbial species present are known or that is germ-free (e.g., mammalian fetuses in utero are free from microorganisms) Gnotobiotic animals allow investigation of the interactions of animals with specific microorganisms that are deliberately introduced into the animal Gnotobiotic colonies of mammals are established by cesarean-section delivery in a germfree isolator; germ-free bird colonies are established by sterilizing egg surfaces and then hatching the eggs in sterile isolators; gnotobiotic colonies are kept in a sterile environment, and normal mating and delivery (hatching) of gnotobiotic animals maintains the colony Gnotobiotic animals are not anatomically or physiologically normal Can have poorly developed lymphoid tissue, thin intestinal walls, enlarged cecum (birds), or low antibody titers Require nutritional supplements Have reduced cardiac output and lower metabolic rates Are more susceptible to pathogens, but may be resistant to diseases caused by protozoa that use bacteria as a food source (e.g. Entamoeba histolytica) and dental caries Normal Microbiota of the Human Body Internal tissues are normally free of microorganisms; however, many other sites are colonized; normal microbiota are the microorganisms regularly found at any anatomical
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This note was uploaded on 06/07/2011 for the course EE 80119 taught by Professor Bakta during the Spring '11 term at University of Zagreb Faculty of Electrical Engineering and Computing.

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10-peranan-mikroba - 1 CATATAN KULIAH KE-14 PERANAN...

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