Microbiota of the GI Tract Flashcards
What alters microbial populations throughout the GI tract?
Transit time
O2 presence
pH5
How does transit time affect the gut microbiota?
A section with a rapid transit time won’t have slow growing bacteria residing there
What is a Facultative anaerobic bacteria
Can grow in the presence of oxygen AND in the absence of oxygen
[Some may grow poorly]
Obligate anaerobe ?
Cannot grow in the presence of oxygen
– many rapidly killed in the presence of any oxygen
How does O2 affect gut microbiota?
As the gut gets more anaerobic - bacterial populations change form facultative to obligate
What effect does pH have?
Different parts of GI tract have different pHs
Hence bacteria who favour a certain pH will be found in a certain area
What are the functions of the GI microbiota?
Metabolise dietary components/produces essential metabolites
Modify host secretions e.g. mucins and bilirubin
Defends against pathogens
Immune system priming
Host signalling
How does the gut microbiota protect against pathogens?
Direct competition
Training immune system
Barrier function - a pysical barrier
pH inhibition
How do gut bacteria provide pH inhibition?
Pathogenic bacteria usually grow at pHs over 6
Gut bacteria break down cellulose to short chain FFAS which lowers pH
Why is the presence of bacteria important for the gut?
Fight pathogens
Provide important metabolites
What happens if the gut flora is disturbed?
disrupts the homeostasis of the gut and lead to inflammation
How do antibiotics affect the microbiota?
Broad spectrum ones have a neg. effect and can lead to issues with:
- Pathogenic infections
- Maintaining immune function
- Signalling molecules
- With metabolites
What is CDAD?
Clostridium Difficile Associated Diarrhoea
How do we treat dysbiosis of the gut microbiota?
Faecal Microbial Transplant - inserts the right commensal bacteria back in
Do we have more microbial cells or human cells?
Microbial
