Microbiota of GI Tract Flashcards
why are more bacteria typically found the further down the GI tract you go
cause longer transit times yo :)
describe the oxygen availability as you go down the GI tract
increasingly anaerobic conditions
probiotics
live bacteria
where can anaerobic bacteria exist
grow in the presence of oxygen and absence of oxygen
where can obligate anaerobes grow
cannot grow in presence of oxygen
pH mouth
6.5-7.5
pH stomach
1.5-4
pH duodenum
7-8.5
pH colon
5.5-6.5
pH small intestine - duodenum
4 -> 7
explain the usefulness of knowing phyla of bacteria
less useful than knowing something is a mammal; could be an elephant, vole, platypus and ya wouldnae know
what level do meaningful comparisons of bacteria have to take place at
genus level
what do GIT microbiota do? their function etc.
metabolism of dietary components
production of essential metabolites
modification of host secretions
defence against pathogens (competition etc.)
development of immune system
what type of food doesn’t provide any energy to our gut microbes
junk food
what do GIT microbes like to grow on
grow on fibre
energy absorb ed in large intestine
what percentage of energy is absorbed in stomach/ small intestine
70%
what percentage of food is absorbed in the large intestine
5-10%
health protection benefits of including fibre in our diet
improves faecal bulking, improving passage resulting in shorter transit time
contains important chemicals, vitamins etc/
feeds our bacteria
results of bacterial fermentation
- releases additional phytochemical
maintains slightly acidic pH
increased commensal bacteria population and pH improves resistance to pathogens
essential supply of short chain fatty acids
effect of branched short chain fatty acids on your health
have a negative impact
how to gut microbiota provide defence against pathogens
- barrier effect (large numbers of host bacteria prevent colonisation by ingested pathogens)
- active competitive exclusion
what is optimum growing pH for pathogens
> 6
why don’t pathogens tend to be present in proximal colon
pH too low
