Gut Microbiota and Immunity Flashcards
(36 cards)
What are the three levels of gut defence?
- Physical - skin
- Innate immunity - non-specific
- Acquired immunity - B-cells and T cells
What are the 5 main host defences in the GI tract?
- mouth
- oesophagus
- stomach
- small intestine
- large intestine
What are the host defences of the mouth?
- Flow of liquids
- Saliva
- Antimicrobials
- Microbiota
What are the host defences of the oesophagus?
- flow of liquids
- peristalsis
What are the host defences of the stomach?
- acid pH
- antimicrobials
- mucus (goblet cells)
What are the host defences of the small intestine?
- flow of gut contents
- peristalsis
- mucus
- bile (acidic)
- secretory IgA
- Antimicrobial peptides
- Microbiota
What are the host defences of the large intestine?
- microbiota
- peristalsis
- mcus
- shedding and replication of epithelium
Describe a commensal relationship?
- host = ok
- bacteria = happy
Describe a symbiotic relationship
- host = happy
- bacteria = happy
Describe a parasitic relationship
- host = unhappy
- bacteria = happy
What are the three main probiotic bacteria?
- Lactobacillusspp.
- Bifidobacteriumspp.
- Bacteroidesspp.
What is the meaning of probiotic?
greek “for life”
“friendly bacteria”
What is the action of probiotics?
produce bacteriocins - end product of cabohydrate fermentation
What are the main benefits of prebiotics and probiotics?
- synthesis of vitamins
- metabolism of bile acids
- production of short-chain fatty acids
- reduction in pH of large bowel
- immune system activation
- development of mucosal barrier
What is the role of gut microbtioa?
- Prevent colonisation by pathogens
- Excrete useful metabolites
- Ferment unused energy substrates
- Synthesise and excrete vitamins
- Produce hormones
Draw a diagram indicating the factors that contribute to a healthy gut microbiota
What are the main factors controlling gut microbiota?
- Physiological status
- Underlying disease
- Intestinal secretions
- Intestinal motility
- Immune mechanisms
- Environmental factors
- Use of antibiotics
What is the primary immune organ in the body?
GI tract
contains 60% of total immunoglobulins and >10million lymphocytes per gram tissue
What has a strong influence on the development of the local systemic immunity and the regulation of immune functions?
GI microbiota
What four main pathogen recognition receptors?
- PAMPs / MAMPs: pathogen / microbe associated molecular patterns
- TLRs: Toll-like receptors
- NODs: nucleotide-binding oligomerization domain-containing proteins
- NLRs: NOD-like receptors
How are most GI tract infections acquired?
faceal-oral route
When does infection occur?
when a pathogen causes ill health
What must pathogens overcome to cause infection?
host defences and compete with microbiota
What can become pathogenic if the conditions are right?
commensals
