What is the transit time in the mouth?
What is the transit time in the oesophagus?
What is the transit time in the stomach?
What is the transit time in the small intestine?
What is the transit time in the colon?
10 hours to several days
What does transit time affect?
Bacterial populations due to different bacterial growth rates
Intestinal cell exposure to toxins, consumed with food or produced by bacteria
How does the amount of bacteria change as you go down the GI tract from the stomach to the colon?
What does anaerobic mean?
Living in the absence of oxygen
What does aerobic mean?
Living in the presence of oxygen
What are different classes of anaerobic bacteria?
Facultative anaerobic bacteria
Obligate anaerobic bacteria
What are facultative anaerobic bacteria?
Can grow in the presence of oxygen and in the absence of oxygen (some grow poorly when oxygen is present)
What are obligate anaerobes?
Cannot grow in the presence of oxygen (many rapidly killed in the presence of oxygen)
What are examples of bacteria found in the stomach?
What are examples of bacteria found in the colon?
What class of anaerobes are found in the stomach?
What class of anaerobes is found in the colon?
Why do different kinds of bacteria dominate different areas of the GI tract?
Different oxygen concentrations
Different transit times
How does the number of microbial cells compare to human cells?
There are more microbial cells
How much bacteria is there in the human gut?
What are the different parts of taxonomy?
Why must meaningful comparison between bacteria be done at the genus level?
Bacterial comparison at the phylum level is a higher level than grouping all mammals together
What impact does diet have on bacteria?
What does OTU stand for?
Operational taxonomic unit
What does a higher number of OTUs mean?
How are the vast majority of bacteria in the GI tract beneficial for health?
Different bacteria perform different functions
Bacteria act together in a population
Bacteria communicate with each other and with the host
A diverse microbiota is important to maintain health
What are some functions of gut microbiota?
Modifications of host secretions (mucin, bile, gut receptors etc)
Defence against pathogens
Metabolism of dietary components
Production of essential metabolites to maintain health
Development of the immune system
How does the gut microbiota provide defence against pathogens?
What host secretions do the gut microbiota modify?
Why is junk food bad although it contains lots of energy (calories)?
Does not feed out gut microbes, that grow on fibres
What kinds of food is fibre found in?