Module 9: The Microbe-Human Ecosystem Flashcards
what is a holobiont
the community of microorganisms coexisting in humans
what is a microbiota
- ecological communities of commensal, symbiotic and pathogenic microorganisms found in or on a multicellular organism
what influences host metabolism
- host body weight is more closely related to the number of calories absorb rather then eat
- would it be possible to change your microbiota to break down different foods to loose weight
what influences host immunity
disruption of GL tract microbiotics by antibiotics allows for pathogens to gain a foot hold = colonizing resistance
- involces changes the local environment to to changes in metabolic patterns
what is the difference between direct and indirect colonization resistance
direct = operates through interactions between microbs
indirect = operates through the induction of the host cell response, such as interation result from responses to products released by the microbiota
what is the influence on neural host cells
- GI microbiome products in the development and functioning of the brain and nervous system via the gut brain axis
- some microorganisma have the ability to return this axis to normal
what is Dysbiosis
- alteration in the microbiome that has a negative impact on the health of the host
what is the process of infection
- organism is multiplying on or in a larger organism host
- when affected agent causes a disease state in the host its a pathogen
- organisms ability to causes a disease state is pathogenicity
- degree of harm is virulence
what is a opportunistic pathogen
- normal residents of the microbiota can occasionally be the cause of the pathogen
what is an extracecullar pathogen
organisms that grow and survive in/on host without entering into a host cell
what is an intracellular pathogen
- pathogens that can grow and multiply within host cells
- viruses
what are pathogens called that can survive inside and outside of the cell
- facultative intracellular pathogens
what is a obligate intracellular pathogen
- cannot grow outside of a host cell
- this is tricky to cultivate in a labratory setting
what is the first stage of infection
- incubation period = non resident pathogens,infectious prcess starts with initial exposure and successful pathogen entry and stable maintenance at its specific niche. intitial entry anf first signs (pathogen is replicating, but has not reached a level sufficient to cause sufficient host damage/response to be detected
what is the second stage in infection
- prodromal period = first onset of symptoms for many infections and not clear enough to make a diagnostic
what is the third stage of infection
- illness period = symptoms are most severe and characteristic to the type and site of infection
- typically this stage is when adaptive immune response is triggered
- if the illness progressively worsens without the patient being able to overcome it = death
what is the finale stage in infection
- convalescene period = symptoms begin to dissapear
- immune reponse begins to gain the upper hand
what are the three types of transmission
- airborne - the pathogen is suspended in air as droplets of dust - repiratory tract, mucos membrane or open wound
- contact - direct contact with individual or object, (fomite for object carrying disease) = vihicle transmission
- vector borne - a biting athropod
what is adhesion
- ability to bind or adhere to the host cell or body site
what is infectivity
- ability of the pathogen to get its niche, bind and establish itself as a point of infection
what is invasion
- invasion = process of organism moving to additional or adjacent tissues beyond site of invasion
some active processes that require enzymes and/or toxins produced by the pathogen such as:
- attacking the extracellular matrix and baseent membranes or intestinal linings
- degrading carbohydrate-protein complexes between cells or on cell surface, disrupting host cell
other pathogens spread passively when the opportunity arises
- small breaks in muscle membranes
- wounds, burns or abrasions on the skin
- arthropod vector bite wound
- separation of tight junctions between host cell during inflammation
- tissue damage caused by other organisms or injury
what is septicemia
- presence of bacterial or fungl toxins in the blood
survival of host defences can cause
- destroying competition
- hiding from detection
- evading and detection/destruction
- distracting immune reponses
- suppressing the host immune reponses
what is biofilm
- a common way for pathogens to avoid the immune response
- protective environment
why do we worry about infectious disease
- their presence damages the host in some way
how can genes become advantageous
- they enhance a microorganisms virulence and can be transfered by horrizontal transfer to new organisms
pathogenicity islands
what is toxigenicity
- ability to produce toxins
- intoxicants are diseases that result from a specific toxin
what is an exotoxin
- heat labile
- release into host tissue during pathogen growth
- actively secreted by producing pathogen and can travel from sites distant from infection
- types of toxins can be grouped together by thei mode of action or by relatedness of their protein sequence or structure
what is a super antigen
- targets T cell activation by coupling the t cell receptor with MHC molecules on antigen presenting cells in a manner that results in T cell activation, even in absence of a bound peptide
- massive T cell response is toxic to the host
what is an endotoxin
- toxic effect is not dependent on an action of the toxin but on host reponse to the toxin
- initiator of septic shock
what is a mycotoxin
- produced by fungi
- contaminate agricultural crops, or water
aflatoxins - typically cause molds which can interfere with neurological functions in large amounts
