gut axis Flashcards by Heena Patel

microbiota

collection of micro-organisms colonising a particular part of the human body for example:
-skin bacteria
-gut bacteria

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what 4 groups do microorganism’s categorise in ?

1.bacteria
2.archea
3.eukaroyotes(fungi, Protozoa)
4.viruses

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Microbiome (what collections does this include ?

1.collection of microorganism 2.collective genomes
3.gene products (signalling molecules , toxins ) of microbes living on or within humans

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what 3 microbes are involved Human gastrointestinal tract ?

1.bacteria
2.eukaryotes(yeast)
3.viruses

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how many protein coding genes are included in a human genome?

2300- each cell contains the same genetic material

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what are the classifications of GI tract commensal bacteria -taxonomy

-Domain -eukaryote
-Kingdom-bacteria
-Phylum-firmicutes
-Class-Bacilli
-Order-Lactobacillales
-Family- Lactobacillaceae
-Genus-Lactobacillus
-Species- Lactobacillus acidophilus

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what spheres does the bacteria spheres(COCCI)
(5 names)

1.streptocci
2.diplococci
3.tetrad
4.staphylococci
5.sarcina

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what bacteria does RODS include? (3 names)

1.chain of bacilli
2.flagellate rods
3.spore-former

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what 3 things does the bacteria spirals include?

1.vibrios
2.spirilla
3.spirochaetes

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what are the 2 main commensal bacteria in the human tract?

firmicutes
bacteroidetes

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what 3 things does the clostridium include?

-clostridium
-lactobacillus
-enterococcus

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what are 3 bacteria shapes?

1.spheres
2.rods
3.spirals

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what percentage of the gut bacteria does firmicutes and bacteroidetes

90%

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what percentage of the gut bacteria does actinobacteria, proteobacteria, fusobacteria & verrucomicrobia make?

10%

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actinobacteria

Bifidobacterium
(cleft into 2 parts)

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what 4 things does gut microbiota changing along the GI tract depend on?

1.pH
2.Digesta flow rates (high in mouth, slow in colon)
3.Substrate availability
4.Secretions (e.g.; bile in the small intestin)

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what are most bacteria

anerobic

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where is the largest gut microbiota found in?

large intestine

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what 4 things does tract microbiome impact?

1.delivery & other conditions
2.diversty
3.microbiota diversity in adult age
4.microbioata diversity in older people

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how does Delivery & other conditions help associated with mother?

(e.g.; milk, health, diet) provides a child’s first microbiota (& microbiome)

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how does diversity increase with age?

At 3 years of age, a child’s gut microbiota composition & diversity is similar to most adults

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is Microbiota diversity stable in adults?

it is stable in healthy adults

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how is microbiota diversity affect older people?

decreases in older people

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what factors influence the GI tract microbiome

-hormone levels
-lifestyle
-breast milk versus formula
-genetic factors
-age specific factors
-stress
-antimicrobial peptides

what are the 5 roles of GI tract microbiota

1.neruo 2.infectious diseases 3.metabolic disease 4.inflammatory disease 5.liver disease

what system is the enteric nervous system?

Autonomous Nervous System (ANS)

function of the enteric nervous system?

Communicates with CNS via the Parasympathetic (e.g.; vagus nerve) and Sympathetic Nervous Systems and the Sacral (pelvic) plexus

what GI tract 2 functions does the enteric nervous system control ?

1.muscle contraction 2.gastrointestinal secretions)

enteric nervous system structure

-lamina propria: protected by mucus- where the GI tract vili can be found that are in contact with the nutrients and microbiota

what 2 layers are important for the function of the ENS

1.submuscosa plexus 2.Myenteric plexus

submuscosa plexus

neuronal function of E&S are found

what are between the 2 layers:submuscosa plexus and Myenteric plexus?

intestinal muscle layers -a longitudinal one -a circular one

what are the function of E&S ?

both plexuses are composed of: -sensory neurones -interneurones -motar neurones

sensory neurones

detect mechanical (mechanosensitive neurons) signals and chemical (chemosensitive neurons) stimuli (amino acids

interneurones

connect sensory and motor neurons

motor neurones

are excitatory or inhibitory; project to the various muscle layers and affect motility or secretion

What is the function of a myenteric plexus

regulates the motility of circular and longitudinal muscles

what is the function of a submucosa plexus?

controls : 1. ion and water secretion, absorption or ions, vitamins and nutrients; 2. release of endocrine and paracrine mediators

what 3 things does the ENS act through ?

1.neurotransmitters 2.neuropeptides 3.neuromodulators

what are 2 healthy conditions of healthy GI tract

-protective mucus -functional tight junctions -ensure the integrity of intestinal barrier

what happens in a leaky gut

the villi can change morphology alters the contact between GI tract itself and microbiota- this happens in a leaky gut

what 2 things can a damaged GI tract lead to?

-impaired tight junctions -altered microbiota/microbe

in which 3 ways can the CNS affect the GI tract microbiome?

1.Modulating gut motility (transit) 2.Changing intestinal secretions (hormones) 3.Altering gut membrane permeability

what are some diseases that lead to effects of the CNS on the gut microbiome ?

1.gastrointestinal disease 2.irritable bowel syndrome 3.slow transit constipation

what 3 different animal modals are there

1.germ-free mice: they have no gut bacteria 2.gnotobiotic mice:germ free mice -often referred to define flora mice 3.specific pathogen free mice-they only tested for common pathogens in the ill -useful since they don't have any microbiota.

what part of the brain can microbiota change

gene expression e.g. decrease in hippocampul activity

what are 2 changes in the brain when affected by gut microbe

-alteration of metabolite levels e.g. tryptophane and hormonal levels such as leptin -alteration of neruotransmitters and their receptor expression levels such as serotonin

what 3 things is Autism spectrum disorder(ASD) characterised by?

social deficit repetitive behaviour language difficulties

what is another mechanism involved in the guts brain axis ?

-deregulation of an individual's immune responses

how does inflammatory impact the leaky gut ?

GI microbiota is changed the signals , which are received by immune cells are different -this will induce a change in the molecule produced by immune cells

what are probiotics

live bacteria people call good for health

why did the germ free mice have better gut microbiota

they have less fat mass

how does diet effect the microbiota

increased dietary fat and sugar(western diet) induced a drastic shift in the composition of the gut bacteria

what appetite suppressor has an impact on fat mass have an impact on hut microbiota ?

leptin -small hormone secreted by the adipose tissue -it activates the POMC neurones which decreases an individual's appetite it also inhibits AGRP neurones and can activate food intake

what happens if the pomc neurones do not respond to insulin?

then the appetite will be not decreased

What happens if AGRP neurones do not respond to leptin

then they are not inhibited and therefore activity appetite is not switched of

how can changes in the gut impact feeding behaviours ?

increasing inflammation in the hypothalamus -adipose tissue is also inflamed-increased levels of inflammatory molecules , these molecules will impact the gut bacteria

what does microbiota secrete

cytokines that travel to the brain