exam 1 - detailed

• what is host defense?

  a complex balance, requires recognition of self vs non-self, and protects against disease while maintaining beneficial relationships
• what does saprophytic mean?

  free living microbes
• what does parasitic mean?

  microbes that require a host
• why would saprophytes exist in a higher order host?

  if the living conditions are better
• over 99.99% of bacteria live outside a host
• host microbes are dynamic interactions mean they depend on the characteristics of the microbe and the host
• what does host range mean?

  the range of species that in which a microbe is able to exist
• only a fraction of microbial species are associated with humans (6x10^13 bacterial cells per person)
• what kind of microbes compose the normal flora?

  commensals, opportunistic, and pathogens
• what are commensal microorganisms?

  have a beneficial or neutral relationship with the host
• what are opportunistic microorganisms?

  take advantage of favorable conditions to grow and reproduce
• what are pathogenic microorganisms?

  always cause disease
• what are factors that influence the microbiome?

  diet, antibiotics, anatomic abnormalities, genetic differences, hormonal changes, age, lifestyle and location
• why is the microbiome beneficial to the host?

  protection from pathogens, stimulation of gut maturation, stimulation of innate and adaptive immunity, expansion of nutritional diversity, digestion of complex carbohydrates
• how do microbiomes protect the host from pathogens?

  stable ecosystems resist introduction or overgrowth of pathogens at epithelial surfaces
• what are the negative consequences of the microbiome?

  foot odor, flatulence, body odor, bad breath, opportunistic disease, transfer of antibiotic resistant genes to pathogens
• what is disease?

  any condition in which the normal structure or functions of the body are damaged or impaired
• are physical injury and disability classified as disease?

  no
• what are causes of disease?

  infection, genetics, environmental and immune responses
• what is infection?

  successful colonization of a host by a microorganism, can lead to disease
• what are pathogens?

  organisms that cause disease
• what is virulence?

  the degree of pathogenicity
• what historical account of disease occurred in 3200 BC?

  shememsu of egypt, first recorded epidemic with unknown cause
• what historical account of disease occurred in 400 BC?

  plague of Athens, could have been caused by measles or typhus
• what historical account of disease occurred in 80 AD?

  epidemic in livestock and humans in italy, could have been caused by anthrax
• what historical account of disease occurred in 1546?

  germ theory, seeds of disease
• what historical account of disease occurred in 1665-1786?

  Hook, Leeuwenhock, and Mueller discovered animalcules
• what historical account of disease occurred in 1840?

  germ theory plus, contagion is living and may be cultivated outside the host
• what historical account of disease occurred in 1860-1864?

  formal experiments conducted by Louis Pasteur
• what historical account of disease occurred in 1876?

  Koch's postulates
• what are Koch's postulates?

  the microorganism must be present in every case of the disease but absent from healthy organisms

  the suspected microorganisms must be isolated and grown in pure culture

  the same disease must result when isolated microorganism is inoculated into a healthy host

  the same microorganisms must be isolated again from the diseased host
• what are the stages of pathogenesis?

  exposure, adhesion, and invasion
• what is exposure?

  encounter with pathogen, requires a portal of entry to gain access to the host
• what are portals of entry and why are they important for pathogenesis?

  broken skin, mucous membranes, and parenteral routes

  pathogens are suited to particular portals of entry
• what is adhesion?

  attachment to body cells, mediated through adhesins, bind to receptors on host cells, or biofilms can cause adhesion
• what are examples of adhesins on the surface of pathogens?

  fimbriae, bacterial flagella, cilia, viral capsid or envelopes, viral spikes, capsules
• what is invasion?

  mediated production of exoenzymes or toxins, dissemination throughout local tissues or body, and damage host to spread deeper
• what are exoenzymes and toxins examples of?

  virulence factors
• how do pathogens generally disseminate?

  through the blood stream, can lead to sepsis
• what is dissemination through the blood stream referred to as?


  emia