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Gastrointestinal > 16. introduction to the Gut Microbiota > Flashcards

16. introduction to the Gut Microbiota Flashcards

1
Q

when is our GUT MICROBIOTA ESTABLISHED

A

in first few years of life
(but fragile)

(especially first 10 days)

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2
Q

our MICROBIOTA CO-EVOLVE with…

A

the IMMUNE SYSTEM

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3
Q

MICROBIOTA GENE SET is how many times the HUMAN GENOME

A

150X

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4
Q

MICROBIOTA are IMPACTED by

A

*DIET

  • ENVIRONMENT
  • HOST GENOTYPE
  • AGE (fragile again later in life)
  • DISEASE
  • type of birth, type of feed (breastfeed)
  • Inflammation
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5
Q

how is a FETUSES FIRST FAECES - MECONIUM

A

STERILE
no microbiomes

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6
Q

on DAY 2 of life which BACTERIA could be isolated

A
  • COLIFORM BACTERIA eg E. COLI (first colonisers)
  • LACTOBACILLI (in breast milk and vagina)
  • ENTEROCOCCI
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7
Q

STRAINS of which BACTERIA can be found on DAY 3

A

BACTEROIDES

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8
Q

which BACTERIA be found on 5TH DAY

A

BIFIDOBACTERIA

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9
Q

GUT MICROBIOTA SHAPES INTESTINAL…

A

IMMUNE SYSTEM

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10
Q

how is GUT MICROBIOTA is HEALTHY INDIVIDUALS

A
  • HIGHER TAXONOMIC DIVERSITY (number and relative abundance of species in a community)
  • HIGHER GENE DIVERSITY
  • Microbial communities are important for DEVELOPMENT and STABILITY of IMMUNITY
  • HOST-MICROBIOTA MUTUALISM
  • Bacteria CONTROLLED BY the INTESTINAL BARRIER (mucus) and underlying MUCOSAL IMMUNE COMPARTMENT
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11
Q

what is meant by HOST-MICROBIOTA MUTUALISM

A

2 ORGANISMS of DIFFERENT SPECIED CO-EXIST
& each individual BENEFITS from the ACTIVITY OF THE OTHER

  • relationship where both benefit from each other
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12
Q

what are BACTERIA in our GUT MICROBIOTA CONTROLLED BY

A

INTESTINAL BARRIER and UNDERLYING MUCOSAL IMMUNE COMPARTMENT

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13
Q

name the 6 MAJOR PHYLA (level of classification or taxonomic rank)

A

90%:
- FIRMICUTES
- BACTEROIDETES

lower numbers:
- ACTINOBACTERIA
- PROTEOBACTERIA (can become pathogenic)
- FUSOBACTERIA
- VERRUCOMICROBIA

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14
Q

what are the DOMINATING BACTERIA in the DISTAL GUT especially Ascending and Transverse COLON

A

FIRMICUTES and BACTEROIDETES

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15
Q

how is the MUCUS LAYER in the COLON

A

2 LAYERS
Inner: free from bacteria
Outer: legislator of HOST-MICROBIAL INTERACTIONS (bacteria present)

& CONTINUOUS

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16
Q

2 MUCUS LAYERS in the COLON are ORGANISED by which MUCIN GLYCOPROTEIN

A

MUC2 MUCIN

17
Q

which COLON MUCUS LAYER has BACTERIA

A

OUTER LAYER

18
Q

WHERE is MUCUS CONTINUOUS / DISCONTINUOUS

stomach?
small intestine?
colon?

A

CONTINUOUS in STOMACH & COLON

DISCONTINUOUS in SMALL INTESTINE (for efficienct absorption)

19
Q

why are HIGH FRUIT, LEGUME and FIBRE DIETS beneficial for GUT HEALTH

A

more GRAM+ bacteria
more saccharolytic species (anaerobic)
(& less pathogenic intestinal bacteria)

HIGH SCFA LEVELS (short-chain fatty acids)

20
Q

SCFAs are a subset of FATTY ACIDS with how many CARBON MOLECULES

A

6 OR LESS

21
Q

SCFAs in bowel

A

ACETATE
PROPIONATE
BUTYRATE (main source of energy)

22
Q

SCFAs from bowel are taken up into circulation and then FURTHER METABOLISED by…

A

LIVER

23
Q

what can you get from ANUMAL BASED DIET

A

HARMFUL BRANCHES ISO- SCFAs

24
Q

where are SCFAs ABSORBED

A

LARGE INTESTINE

25
Q

SCFA UPTAKE by which TRANSPORTER/RECEPTOR

A

MCT (monocarboxylate) TRANSPORTER/RECEPTOR

26
Q

how can SCFA be ABSORBED

A
  • MCT TRANSPORT/RECEPTOR - transcellular
    or
  • DIFFUSION through APICAL MEMBRANE
    and TIGHT JUNCTIONS
27
Q

MAJOR SOURCE of ENERGY for the BOWEL

A

BUTYRATE

28
Q

BUTYRATE (BT)also acts as

A

POTENT INHIBITOR of HISTONE DEACETYLASES (HDAC)

ENHANCES TUMOUR SUPPRESSOR GENE EXPRESSION
- ANTI-CANCER agent

29
Q

SCFA RECEPTORS are what type of receptors

A

G-PROTEIN COUPLED

30
Q

SCFA RECEPTORS REGULATE..

A

METABOLIC ACTIVITY of gut MICROBIOTA and act as sensors for ENERY EXPENDITURE / CONTROL energy

  • link metabolic activity of gut microbiota with host body energy homeostasis

also SENSE NUTRIENTS - SCFA LEVELS

31
Q

SCFA RECEPTORS can also MODULATE…

A

IMMUNE SYSTEM

  • IMMUNOMODULATORY
32
Q

SCFA entering PORTAL VEIN under-go …. by the LIVER

A

FIRST-PASS METABOLISM

33
Q

within LIVER, SCFA may enter a number of METABOLIC PATHWAYS depending on their metabolic state ie:

A
  • ACETATE and BUTYRATE may be CONVERTED into ACETYL-CoA and used to FORM:
    LIPIDS and KETONE BODIES
  • CITRIC ACID CYCLE used to produce:
    GLUCOSE by GLUCONEOGENESIS
  • ACETATE may pass into PERIPHERAL CIRCULATION and can be DETECTED in PERIPHERAL BLOOD
34
Q

what can ACETATE and BUTYRATE be used to FORM in the LIVER

A

LIPIDS and KETONE BODIES (by conversion into Acetyl Co-A)

or (as well as propionate)
GLUCOSE in citric acid cycle (gluconeogenesis)

35
Q

how does HIGH FERMENTABLE DIET (FRUIT,LEGUME,VEGETABLE, FIBRE) affect BACTERAL DIVERSITY

A

HIGH BACTERIAL DIVERSITY
(more SCFA production)

low diversity in high fat, sugar, animal protein diet (and more amino acid metabolism and more iso SCFAs)

36
Q

DYSBIOSIS (imbalance) is the ALTERATION in MICROBIOME caused by CHANGES IN..

A
  • MICROBIOTA COMPOSITION
  • MICROBIAL METABOLIC ACTIVITY
  • SHIFT in LOCAL DISTRIBUTION of COMMUNITIES of MICROBES
37
Q

when can MICROBIAL BALANCE be tipped towards PATHOGENIC STRAINS (PATHOBIONTS)
(lose homeostasis)

A

REDUCED DIVERSITY
LOSS of BENEFICIAL MICROBES (SYMBIONTS)
PATHOBIONT EXPANSION

38
Q

examples of FACTORA that SHAPE INTESTINAL MICROBIAL COMPOSITION

A
  • CHRONIC INFLAMMATION (IBS,IBD, colorectal cancer, liver disease)
  • METABOLIC DYSFUNCTION (ie diabetes, obesity)
  • IMMUNODEFICIENCY
  • HYPERIMMUNITY
  • ANTIBIOTICS
  • LIFESTYLE (extreme exercise)
  • DIET
  • HYGIENE

Gastrointestinal (19 decks)

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