The microbiota of the alimentary system Flashcards
Is there more microbial cells or human cells on and in the human body?
microbial
What is the most bacterial colonised portion of the GI tract?
The colon - between 10^10 and 10^11 per ml
Is it mainly anaerobes or aerobes found in the colon?
anaerobes
What is an obligate anaerobe?
Cannot grow in the presence of oxygen
What is a faculatative anaerobe?
Can grow in the presence or absence of oxygen
What happens to the bacterial population as you move down the GI tract? (3)
anaerobic conditions
density
obligate anaerobes dominate
What does junk food do for the gut microbiota?
not much as it has lots of calories but most of the energy is taken out in the stomach and small intestine so the gut microbes are not fed
Why is fibre good for gut microbiota?
energy is absorbed in the large intestine and so feeds the gut
Apart from fibre where else can gut bacteria source energy?
endogenous substrates
What does fibre do to faecal bulk and what other advantages do they have?
increase
decrease transmit time and help to produce antioxidants and phytochemicals.
maintain pH and increase the commensal bacteria
What are the 3 main short chain fatty acids produced from fibre in the diet?
butyrate
propionate
acetate
What detects these SCFA?
epithelial cell receptors
What is butyrate needed for?
epithelial cell growth and regeneration
What is propionate needed for?
gluconeogenesis and satiety signalling
What is acetate needed for?
lipogenesis
