Lecture 8 - Microbiota Flashcards
what are commensals and how many do we have as humans
basically good bacteria
no harm to human health
3.8x10^13 bacteria (compared to 3x10^13 human cells)
what is the microbiome
the genome of all the microorganisms in and on our body
how big is the skin
2 square metres
what are the 3 types of bact on the skin
resident bacteria - (skin flora - outdated name)
staphylococcus aureus (origin of MRSA)
transient bacteria (washing ur hands would get rid of these, unlike the others- viruses, poo bacteria etc)
what type of pathogens exist in the nasal cavity
oppurtunistic pathogens
- MRSA
- meningitidis
- influenzae
- pneumoniae
what’s diff about bacteria in oral cavity compared to nasal and skin
vry high biodiversity
lots more species
where do bacteria bind in oral cavity
salivary pellicle receptors
name the bact in stomach that causes gastric ulcers
Helicobacter pylori
gastritis –> cancer (vry small % of people will get this, usually its fine)
in the GI tract, where is majority of bact
colon
10^10 cells per g
what type of bact are vast majority of bact in colon
obligate anaerobes
some facultative aerobes, but they use up all O2 (.g. Ecoli)
what is bacteria dependent in colon between humans
dependent on diet
so a vegetarian has diff bact to carniverous
what bacteria break down oligosaccharides in breast milk
bifidobacter
by what age does childs microbiota becomes liek adult microbiota
3
whats the microbiota change seen in those over 60
increase in Firmicutes
just know that theres a shift in bacteria types (not fully understood yet)
how does bact provide us with 10% of calories from food
the bact convert complex indigestible stuff into short chain fatty acids that we can absorb and use
what does animal body provide bacteri
organic nutrients
growth factors
constant pH, osmotic pressure, temp.
what bacteria causes dental cavities
streptococcus mutans
what is dental plaque consisting of
primary and secondary colonisers
with more anaerobic bact as u go down
why is important to separte small intestine and colon in terms of amount of bact
- al lot less bacteria in SI
-So bact doesn’t compete with us for the nutrients we need.
All the stuff we don’t need go into colon – bacteria will break them down and help us get most amount of stuff from the food
what doe c section lead to a reduced colonisation of
bacteroides and bifidobacterium in gut in early developmet
how is microbiota linked to mood
gut-brain axis (ehich connects CNS w/ enteric nervous system)
stress, depression, obesity, autism
all linked to microbiota
what was ratio of bact in obese mice vs normal mice and why
- obese mice had more firmicutes than bacteriodetes
- so shows the firmicutes better at farming calories
what happened when obese mice treated w/ vancomyocin
- kills gram + bact
- so it killed fermicutes but not bacteriodetes
- lost weight
