Microorganisms and Human Disease – Flashcards
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| Host |
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| Organism which provides nutrients, etc. to another organism. |
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| Parasite |
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| Organism which lives at the expense of (and may even harm) its host; generally smaller than the host and is metabolically dependent upon it. |
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| Disease |
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| An upset in the homeostasis of the host, resulting in generation of observable changes. |
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| Sign |
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| Objective evidence of damage to the host (fever, rash, vomiting) |
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| Symptom |
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| Subjective evidence of damage to the host (headache, anorexia) |
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| Infectious disease |
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| One in which detrimental changes in health of the host occur as a result of damage caused by a parasite. |
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| Pathogen |
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| Microorganism that is capable of causing disease. |
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| Virulence |
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| A measure of pathogenicity. |
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| Pathogenicity |
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| The ability to cause disease. |
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| Virulent Microorganisms |
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| Microorganisms that readily cause disease (only small numbers of the microorganism are required to initiate and sustain infection). |
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| Attenuated Microorganisms |
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| Microorganisms with reduced ability to cause disease. |
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| Avirulent Microorganisms |
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| Microorganisms that do not cause disease. |
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| Opportunistic Microorganisms |
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| Microorganisms that may or may not cause disease. |
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| Adhesins |
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| Enable parasites to attach to host cells or tissues. Promote attachment |
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| Invasins |
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| Enable parasites to enter and/or move through host cells or tissues. Allows bacteria to infect the host |
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| Evasins |
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| Enable parasites to escape from host defenses. |
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| Toxins |
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| Enable parasites to damage host cells. |
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| Prokaryotes |
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| Small, "simple" cells that typically have a cell wall and cytoplasmic membrane that contains ribosomes and a nucleoid comprised of one or more chromosomes with DNA genes. Have no membrane surrounding their nucleoid. |
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| Eukaryotes |
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| Large, "complex" cells with a nucleus that contains multiple chromosomes (with DNA genes) surrounded by a membrane plus cytoplasm containing ribosomes and membrane-bound organelles (mitochondria, endoplasmic reticulum, vacuoles, chloroplasts, Golgi bodies). |
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| Viruses |
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| Acellular (not cells) nonliving entities made up of genetic material (DNA or RNA) enclosed in a protein coat (many also have a membrane called an envelope). They can reproduce themselves only by infecting cells and utilizing cellular materials and processes. |
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| Cell Wall |
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| Rigid structure that protects against osmotic pressure damage and provides cell shape--cylindrical (bacillus); spherical (coccus); helical (spirillum) |
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| Cytoplasmic Membrane |
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| Lipid/protein outer boundary of the cytoplasm regulates what goes in and out of the cell (permeability) |
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| Ribosomes |
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| Small RNA/protein particles required for protein synthesis |
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| Plasmids |
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| DNA that contains only a few genes and is exchanged between bacteria (codes for antibiotic resistance or virulence factors) |
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| Inclusions |
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| Intracytoplasmic storage bodies (may contain phosphates, iron, lipids, etc.) |
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| Capsule |
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| Polysaccharide "coatings" secreted by cells (adhesins) |
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| Flagella |
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| Long, thin protein (flagellin) polymers that provide motility |
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| Pili |
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| Long, thin protein (pilin) polymers that act as adhesins. |
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| Endospore |
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| Thick-walled protective structures; highly resistant to adverse environmental conditions (high temperature, drying, O2, etc.) |
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| Growth |
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| Process of cell enlargement and proliferation (increase in number) |
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| Binary Fission |
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| Proliferation; Division of a cell into two cells of equal size and composition |
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| Epidemiology |
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| study of the occurrence of disease in a human population, especially the cause and transmission of disease |
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| Epidemic |
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| Literally, "upon the people"; commonly refers to an unusually high incidence of a disease in a community (population) at one time. |
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| Prevalence |
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| The proportion (or percentage) of diseased individuals in a population at one time. |
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| Incidence |
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| The number of diseased individuals in a population at one time. |
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| Pandemic |
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| Literally, "all the people"; indicates an epidemic involving more than one continent or a worldwide epidemic |
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| Endemic |
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| Literally, "in the people"; a disease is constantly present, usually at low incidence, in a population |
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| Outbreak |
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| Appearance of several cases of a disease, usually in a short period of time, in an area previously experiencing no cases or only sporadic cases of the disease; "mini" epidemic |
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| Morbidity |
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| Disease; sickness; clinical illness |
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| Mortality |
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| Death |
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| Reservoir |
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| A site in which infectious agents remain viable (alive) and from which infection of individuals may occur. |
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| Carrier |
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| An infected individual which is not showing obvious signs or symptoms of clinical disease, but which is shedding the etiologic agent for a long period of time (greater than six months) |
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| Zoonoses |
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| Diseases which occur primarily in animals but are occasionally transmitted to people |
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| Vector |
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| Living agent which transmits infectious agents |
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| Fomite |
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| Non-living object that transmits infectious agents |
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| Vehicles |
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| Fomites such as food or water |
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| Koch's Postulates |
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| If a microorganism is the causative agent of an infectious disease it must be: 1. Present in every case of the disease, but absent from the healthy host 2. Isolated and grown in pure culture 3. Able to cause the disease when a pure culture is inoculated into a healthy host 4. Re-isolated from the host that was inoculated with the pure culture |
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| Common-source Epidemic |
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| Infection or intoxication of many people from a single contaminated source; characterized by rapid onset, "sharp" peak and rapid decline in incidence |
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| Propagated Epidemic |
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| Introduction of an infected person into a susceptible population leads to transfer of the etiologic agent to others, who transfer it to many others; characterized by a slow onset, "blunted" peak, and slow decline in incidence |
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| Iatrogenic infection |
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| Infections caused as a result of medical procedures which have a good potential to introduce microbes into patient tissues |
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| Nosocomial Infections |
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| Hospital-acquired infections |
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| Innate Host Defense Factors |
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| Non-specific immune (resistance) factors that are present before infection; they work all the time and are effective against many different kinds of microbes |
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| External Resistance Factors |
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| Innate host defense factors which act on body surfaces. |
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| Internal Resistance Factors |
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| Innate host defense factors which act within tissues. |
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| Egestion |
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| Release of non-digestible material |
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| Adaptive Host Defense Factors |
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| Immune factors that are triggered by antigens and are specific for those pathogens to which one is exposed. |
