L28

Question 1

what consists of the gut

Answer 1

stomach: low pH, O2, low diversity + abundance
duodenum: low/neutral pH, low O2, bile, mucus, mon + dissacharides, low diversity, increased abundance
colon: neutral pH, low O2, mucus, polysaccharides, high diversity + abundance

Question 2

gut bacteria and development in humans

Answer 2

neonatal- basically sterile, then through colonisation of gut bacteria via maternal + environmental microbes

perinatal/infant- temporally unstable, simple composition, low diversity

if ill, through malnutrition, + infections, persistent dysbiosis, temprally stable, compositionally simple, low diversity, permissive to pathogens

may recover (or go straight to from infant) health mature (through diet, host genetics, environmental microbes, host immunity), is tmeporarily stable, complex composition, high diversity, resistant to pathogens

could go into transient dysbiosis (acute disturbance, instead of persistent), temporarily unstable, simple composition, low diversity, permissive to pathogens

Question 3

role of bacteria

Answer 3

• bi-directional interactions common (e.g. microbial signalling for immune development functioning immune system for maintaiing health microbiota)
• developing microbiome effects
  -metabolism
  -maturation of gastrointestinal tract
  -immune system function
  • brain developemnt

-general roles
-mantaining homeostasis
- microbial interactions
-resisting pathogens
-inducing tolerance to normal microbiota
-modulating inflammatory + metabolic cascades

Question 4

explain short chain fatty acid production

Answer 4

-fermentaiton as a pathway of eneteric microbiota
-include acetate + butyrate
- stimualtes protective mucus + IgA production
-promotes otlerance bia Treg (immune system doesnt attack gut bacteria)
- inhibit inflammatory mediator
-enhance epithelial abrrier integrity + repair
-promote competitive exculsion of pathogens

Question 5

explain bile acid

Answer 5

• bacteria converts bile acids to 2ndary forms
• somr emore toxic to bacteria, self regulating
• is also signalling molecules, regulates genes alter bile -> after regulation

-modulates
- synthesis of bile acid in liver
transport of bile acid
-lipid + glucose metabolism
-energy homeostasis

receptors etc. for bile acid also found outside of enterohepatic system- including kidney + heart

bile acid processed by bacteria to 2ndary molecules that protect against atherosclerosis

Question 6

how it can go wrong

Answer 6

• lower diversity/changed bacteria
• less scfa -> less mucin + leaky barriers -> bacteria near epithelium + altered signalling -> inflammation + bacterial products into blood stream -> trigger autoimmune diseases (or makes them worse)

could also cause IBD, C.difficule associated diseases, diaebetes, cardiobascular + liver dieases, obesity, mental heatlh- depression

Question 7

how to repair gut bacteria

Answer 7

-nutrition
-prebiotics
-bacteriotherapy
-selective agents- antibiotics + phages

Question 8

explain how obesity affects gut microbita + organs

Answer 8

gut
- altered composition
-altered fermentation
-increased energy harvest

brain
- decreased satiety

liver
- increased short chain fatty acids
- increased inflammation

adipose tissue
- increased triglycerides incorporation
-increased inflammation

muscle
-decreased fatty acid oxidation

epithelium
- increased permeability of epithelium