Gut microbiota and immunity Flashcards
1
Q
What are the levels of gut defences
A
- Physical
- Innate
- Acquired
2
Q
What host defences are there in the mouth
A
- Flow of liquids
- Saliva (contains lysozyme, IgA)
- Antimicrobials
- Microbiota
3
Q
What host defences are there in the oesophagus
A
- Flow of liquids
- Peristalsis
4
Q
What host defences are there in the stomach
A
- Acid pH
- Antimicrobials (e.g. defensins= peptides that can kill pathogens)
- Mucus
5
Q
What host defences are there in the small intestine
A
- Flow of gut contents
- Peristalsis
- Mucus
- Bile
- Secretory IgA
- Antimicrobial peptides
- Microbiota
6
Q
What host defences are there in the large intestine
A
- Microbiota
- Peristalsis
- Mucus
- Shedding and replication of epithelium
7
Q
Give examples of probiotics
A
- Lactobacillus spp.
- Bifidobacterium spp.
- Bacteroides spp.
8
Q
Describe the action of probiotics
A
- Lactic acid producing= it is a metabolic end product that can inhibit the growth of some pathogens
- Product bacteriocins= molecules that kill bacteria
9
Q
What are prebiotics
A
- Non-digestible food ingredients
- Essentially, are carbohydrates that we can’t break down but bacteria can
10
Q
What do prebiotics do
A
Stimulate growth and activity of gut microbiota
11
Q
Effects of prebiotics
A
- Development of mucosal barrier
- Synthesis of vitamins e.g. K
- Metabolism of bile acids
- Production of short-chain fatty acids
- Reduction in pH in large bowel
- Immune system activation
12
Q
How does the density of microbiota change down the GI
A
Increase in density
13
Q
What is the role of gut microbiota
A
- Prevent colonisation by pathogens
- Excrete useful metabolites (e.g. short chain fatty acids)
- Ferment unused energy substrates
- Synthesise and excrete vitamins
- Produce hormones
14
Q
Factors controlling gut microbiota
A
- Physiological status
- Underlying disease
- Intestinal secretions
- Intestinal motility
- Immune mechanisms
- Environmental factors
- Use of antibiotics
15
Q
How does the body recognise pathogens
A
- PAMPs/MAMPs= pathogen/microbe associated molecular patterns
- TLRs= toll-like receptors
- NODs= nucleotide-binding oligomerization domain-containing proteins
- NLRs= NOD-like receptors
