7. Gut Microbiota and Immunity Flashcards
Physical/ innate host defences in the GI tract
- Mouth
- Oesophagus
- Stomach
- Small intestine
- Large intestine
4 features of the mouth as a host defence
- Flow of liquids
- Saliva
- Antimicrobials
- Normal microbiota
2 features of oesophagus as a host defence
- Flow of liquids
* Peristalsis
3 features of the stomach as a host defence?
Acid pH
Antimicrobial
Mucus
7 features of SI as a host defence
- Flow of gut contents
- Peristalsis
- Mucus
- Bile
- Secretory IgA
- Antimicrobial peptides
- Normal bacterial microbiota
4 features of large intestine as a host defence
- Normal microbiota
- Peristalsis
- Mucus
- Shedding and replication of epithelium
Name the 3 host-bacteria relationships and the host/bacteria attitude
Commensal:
Host =Unaffected
Bacteria =Happy
Symbiotic:
Host = Happy
Bacteria = Happy
Parasitic = Unhappy Bacterium = Happy
Probiotics:
Name 3?
Action?
Produce what?
E.g.
• Lactobacillus spp.
• Bifidobacterium spp.
• Bacteroides spp
Action: Alters pH but producing lactic acid
What are prebiotics?
Non-deigestible food ingredients
Stimulate growth / activity of gut microbiota
Functions of probiotics and probiotics?
Development of mucosal barrier Synthesis of vitamins Metabolism of bile acids Production of short-chain fatty acids Reduction of pH in large bowel Immune system activation
Role of gut microbiota (5)
- Prevent colonisation by pathogens
- Excrete useful metabolites
- Ferment unused energy substrates
- Synthesise and excrete vitamins
- Produce hormones
A flourishing gut/ecosystem –> Devastation by ______ —> Left alone –> Prebitiocs, probiotics, ______ —> Restored ecosystem
A flourishing gut/ecosystem –> Devastation by ANTIBIOTICS —> Left alone –> Prebitiocs, probiotics, BACTERIOTHERAPY —> Restored ecosystem
Factors Controlling Gut Microflora (7)
Physiological status • Underlying disease • Intestinal secretions • Intestinal motility • Immune mechanisms • Environmental factors • Use of antibiotics
Primary immune organ in the body?
GI tract
GI microbiota has a strong influence on the development of the local and systemic immunity and in the regulation of immune functions
Name 4 features associated with pathogen recognition?
- PAMPs / MAMPs: pathogen / microbe associated molecular patterns
- TLRs: Toll-like receptors
- NODs: nucleotide-binding oligomerization
domain-containing proteins - NLRs: NOD-like receptors
What are the gut microbiota- gut mucosa interactions?
Commensals and pathogens can induce local immune response.
Stimulates release of NK-kB
–>
Transciption of pro-inflammatory genes
–> Secretion of cytokines and chemokine such as TNF and IFN-gamma
NF-κB is a protein complex that controls transcription of DNA, cytokine production and cell survival
Diarrhoea:
What is it?
Cause?
Results in?
What is it? Abnormal faecal discharge characterised by frequent and/or fluid stool.
Cause? Result of disease in small intestine
Results in? Involves increased fluid and electrolyte loss
Dysentery:
What is it?
Due to?
Associated symptoms?
What is it?
Inflammation disorder of GI tract
Due to:
Disease of large intestine / infection
Associated symptoms:
- Blood and pus in the faeces
- Pain
- Fever
- Abdominal cramps
Classification method for stools?
Bristol stool chart
Type 1-7 (hard small lumps –> entirely liquid)
Acquisition of intestinal infection
Ingestion of infected food and water
Ingestion of bacterial toxins
Use of oral antibiotics
What are the symptoms of gastroenteritis? 4
Nausea
Vomiting
Diarrhoea
Abdominal discomfort
What is enterocolitis?
Inflammation involving the mucosa of both and large intestine
