The Human Microbiome Flashcards
define colonisation
the establishment of microorganisms at a site in the body
define human microbiome
the microbes that live in and on the body
define resident microbiota
organisms which are found at a given location in a state of health
define symbiosis and the 3 types
when 2+ organisms co-exist in close physical association
mutualism
- reciprocal benefit
parasitism
- one side benefits - large degree of harm to the host
commensalism
- least association
- used for shelter and food
define dysbiosis
an imbalance in the resident human microbiota
define pathobiont
a member of the resident microbiota that causes disease when there is a loss of the normal balance and dysbiosis
define opportunistic infection
when an infection is caused by an organism which is a member of the normal microbiota or normally inhabits the external environment
what is a sterile site?
an area in which there are no microbes present.
what is a non-sterile site?
a site directly or indirectly exposed to the environment
which body sites are normally colonised/non-sterile?
conjunctiva
oral cavity
pharynx
vagina
skin
GI tract
how are sterile and non-sterile sites maintained?
- non-sterile - there are no mechanisms
sterile
- surface cleaning - areas open to enviornment
- barriers which allow uni-directional flow - sphincters
- physical separation - closed cavities
what body sites are normally sterile?
- surface cleaned
= lower respiratory tract - uni-directional flow
= middle ear - eustacian tube
= upper genital tract - cervix
= urinary tract - urethra
= hepatobiliary tract - sphincter of oddi - the liver, gall bladder and bile ducts - physical separation
= pleural cavity
= peritoneal cavity
= spinal cord and meninges
what can be the harmful effects caused by a distressed microbiome?
opportunistic infections may occur
what 6 factors affect the microbiome?
- moisture
- temperature
- pH
- o2 availability
- nature of the surface
- surface turnover
what is tropism
an orientation in response to a external stimulus
