Gut Microbacteria and Immunity Flashcards
What are the levels of gut defences?
- Physical
- Innate immunity
- Acquired immunity
What are the host defences in the mouth?
- Flow of liquids
- Saliva
- Antimicrobials
- Microbiota
What are the host defenses in the oesophagus?
- Flow of liquids
- Peristalsis
What is the pH of the stomach?
2
What are the host defenses in the stomach?
- Acid pH
- Antimicrobials
- Mucus
What is hypochlorhydria?
Production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low
What are the host defenses in the small intestine?
- Flow of gut contents
- Peristalsis
- Mucus
- Bile
- Secretory IgA
- Antimicrobial peptides
- Microbiota
What are the host defenses in the large intestine?
- Microbiota
- Peristalsis
- Mucus
- Shedding and replication of epithelium
What does it mean if a bacteria is “commensal”?
- Derives food or other benefits from an organism without hurting or benefitting it
- May become pathogenic if circumstances are right
What does it mean if a bacteria is “symbiotic”?
It benefits the host and the bacteria
What does parasitic mean?
The bacteria benefits from the relationship whereas the host is harmed by the relationship
What are probiotics?
- A bacteria which is introduced into the body for its beneficial qualities
- Lactic acid-producing
- Produce bacteriocins
Give 3 examples of probiotics?
- Lactobacillus spp.
- Bifidobacterium spp.
- Bacteroides spp.
What are prebiotics?
- Non-digestible food ingredients
- Food/nutrients for gut bacteria
- Stimulate growth and activity of gut microbiota
As you go down the GI tract what happens to the density of bacteria?
Increases
- Oesophagus 10^3 - 10^5
- Large bowel >10^10
How many more bacteria are present in the body than human cells?
There are roughly 10x more bacteria than human cells in the body
What is the role of gut microbacteria?
- Prevent colonisation by pathogens
- Excrete useful metabolites
- Ferment unused energy substrates
- Synthesise and excrete vitamins
- Produce hormones
What is bacteriotherapy?
- The purposeful use of bacteria or their products in treating an illness
What are the factors controlling gut microbiota?
- Physiological status
- Underlying disease
- Intestinal secretions
- Intestinal motility
- Immune mechanisms
- Enviromental factors
- Use of antibiotics
What is the primary immune organ in the body?
- GI tract
- Contains 60% of total immunoglobulins and > 10 million lymphocytes per gram tissue
What substances recognise pathogen/microbe associated molecular patterns (PAMPs/MAMPs)?
- TLRs: Toll-like receptors
- NODs: Nucleotide-binding oligomerization domain-containing proteins
- NLRs: NOD-like receptors
What is NF-kB?
- Transcription factor (nuclear factor kappa-light-chain-enhancer of activated B cells
- Transcribes pro-inflammatory genes
- Secretion of cytokines and chemokines such as TNF and IFNy
What can cause intestinal infection?
- Ingestion of infected food and water
- Ingestion of bacterial toxins
- Use of oral antibiotics
What is enterocolitis?
Inflammation involving the mucosa of both small and large intestine
What is diarrhoea?
- Abnormal faecal discharge characterised by frequent and/or fluid stool
- Result of disease in small intestine
- Involves increased fluid and electrolyte loss
