The Microbiota of the Gut Flashcards
Do conditions in the GI tract become increasingly anaerobic or aerobic?
Anaerobic
Where is most bacterial found in the GI tract?
In the colon
Where is bacterial most variable in the GI tract?
Mouth
What is the transit time of the mouth?
1 min
What is the transit time of the oesophagus?
4-8 seconds
What is the transit time of the stomach?
2-4 hrs
What is the transit time of the small intestine ?
3-5 hr
What is the transit time of the colon?
10hr-several days
What is meant by anaerobic?
Living in the absence of air
What is meant by facultative anaerobic bacteria ?
can grow in the presence of oxygen and in the absence of oxygen
What is meant by obligate anaerobe?
Cannot grow in the presence of oxygen
What is aerobic bacteria?
Living in the presence of air
How does oxygen vary in the GI tract?
Different parts of the GI tract use different concentrations of oxygen
What happens to materials that cannot be broken down and digested by the small intestine?
Will reach the large intestine to be broken down by bacterial fermentation
Where is the site of most carbohydrate fermentation?
Ascending colon
Where do alot of colonic diseases start?
In the distal colon
Give an example of something that has to be broken own by bacterial fermentation?
Cellulose
How does our gut defend against bad bacteria?
The muocous layer forms a barrier between the luminal bacterial population and the epithelial cells
What are the 2 mucous layers surrounding the epithelium of cells?
Inner and outer mucous layer
What does the inner layer of mucous stop?
The penetration of the pathogenic bacteria
What happens to the few bacteria that do penetrate through the epithelium?
They are dealt with efficiently by the immune system
What does a dysregulated immune response lead to?
Inflammation
What is the largest lymphoid organ?
Gut
What is commensal bacteria?
Commensal microflora is an integral part of a complex of natural mechanisms on mucosal surfaces and skin that safeguard the resistance of the organism against pathogenic micro-organisms.
When does autoimmune diseases of the gut occur?
When the immune system can no longer distinguish between harmful detrimental pathogens and commensal bacteria
What is dysbiosis?
Dysbiosis is a term for a microbial imbalance or maladaptation on or inside the body, such as an impaired microbiota.
What type of bacteria predominantly live in the colon?
Anaerobic bacteria
What do resident bacteria do?
Lower pH
Create a physical mucosal barrier
Produce active compounds that kill oncoming pathogens
