gut health Flashcards
what are the roles of the GI tract?
intake of food for energy water absorption waste removal (e.g. by-products of digestion and indigestible components)
at what point in the GI tract are sugars broken down?
oral cavity by enzymes
at what point in the GI tract are fats broken down?
stomach
at what point in the GI tract are proteins broken down and what are they broken down by?
stomach
substrate specific enzymes
what substances mediate digestion (and specify which part of digestion)
enzymes and stomach acid - breakdown sugars, fats and proteins
bile salts - fat absorption
what parts of the body secrete enzymes and give specific examples
mouth - amylase secreted in saliva
stomach - pepsin
pancreas - trypsin, amylases and lipases
what is stomach acid made up of?
salts pepsin mucus intrinsic factor bicarbonate
what is the function of mucus in stomach acid?
forming a layer of the gastric epithelium to prevent the breakdown of the epithelium
what is the function of intrinsic factor in stomach acid?
B12 absorption
what is the function of bicarbonate in stomach acid?
maintaining the pH7 of gastric epithelium
where are bile salts secreted and stored?
secreted by hepatocytes
stored in the gall bladder
Where is the ENS found in the GI tract?
between the oesophagus and rectum
what is the main innervation between the brain and ENS?
vagus innervation
what are the roles of the ENS?
Motility – peristalsis Hormone and enzyme release Nutrient uptake Appetite regulation Vascular flow Immune cell activity
what is the intrinsic innervation?
communication only within the gut
what are the two plexi in the intrinsic innervation?
myenteric
sub-mucosal
where is the myenteric plexus found?
in between outside longitudinal muscle and inside circular muscle
what is the function of the myenteric plexus?
coordinating the contraction and relaxation of muscle to coordinate peristalsis
what can lack of coordination of muscle in the GI tract lead to?
constipation
diarrhoea
motility disorder
where is the submucosal plexus found?
beneath the mucosa
what are the functions of the submucosal plexus?
deal with secretions
nutrient uptake
respond to outside environment through activity of microbiota, nutrients and immune cells
what is the role of interneurons?
allowing connectivity between different types of neurons
which nerve mediates the extrinsic innervation?
vagus
why is the extrinsic innervation known as extrinsic?
its plexiglass lie outside of the gut
communication between the GIT and the brain
what are examples of the plexi of the extrinsic innervation?
oesophageal
coeliac
hypergastric
what do the central terminals synapse with when they enter the brainstem?
neurons of the nucleus tracts solitarus
what effect does the sympathetic nervous system have on the body?
prepares body for stressful responses
what effect does the parasympathetic nervous system have on the body?
controls body during normal situation
where is the largest microbial colony found?
in the colon
what is decreased diversity in the microbiome associated with?
poor health
increased risk of obesity and inflammation
how can bacteria interact with the epithelium?
directly
via their byproducts
how do the microbiota affect the synaptic activity in the brain microglia?
more prone to development of plaques and debris
leads to neurodegenerative diseases
what is the purpose of faecal microbiota transfer?
increase microbial diversity
what are the types of FMT donor?
healthy relative
super donors
artificially produced probiotics
what is FMT used to treat?
C.difficile infection following failure of antibiotic therapy
what % of the population is C.difficile found in?
2-5%
what causes C.difficile infection?
broad-spectrum antibiotic usage
allows for opportunistic over-growth
what are symptoms of C.difficile infection?
abdominal pain
watery diarrhoea
what are the treatments of C.difficile?
stop antibiotic use
vancomycin or metronidazole
FMT
what are prebiotics?
promote growth and survival of bacteria and fungi in the gut
what are probiotics?
live cultures found in dairy products or fermented foods
name common upper GI symptoms
acid reflux, nausea, vomiting, belching, gastroparesis and bloating
name common lower GI symptoms
bloating, constipation, diarrhoea, abdominal pain
what causes GERD
movement of stomach contents from the fungus to the distal oesophagus
occurs when the LOS is relaxed and allows the passage of acid
what is the lower oesophageal sphincter
anatomical valve
what is GERD associated with?
weight gain
stress
gastroparesis
what conditions can GERD lead to?
ulcer formation, inflammation and Barratt’s esophagus
how is GERD treated?
over the counter medications - antacids and alginates (Gaviscon) prescription treatments (e.g. proton pump inhibitors)
what is gastroparesis
Chronic condition where gastric emptying is delayed
what are symptoms of gastroparesis?
nausea, vomiting, rapid feeling of fullness, reflux, pain and bloating
what causes diabetic gastroparesis?
neuropathy of vagal endings innervating the stomach
what can gastroparesis lead to?
malnutrition
formation of bezoars (hardened mass of undigested food)
changes to blood sugar
explain how gastroparesis is diagnosed
Gastric emptying study
- C13 labeled meal is ingested
- Released C13 exhaled in breath - used as marker of food movement through stomach
- Time-course compared to normal values – looking for faster/slower gastric emptying
how is gastroparesis treated?
Domperidone or erythromycin: stimulate stomach muscle contraction
Anti-emetics for nausea
Dietary changes e.g. smaller, more frequent meals, soft foods
what is inflammatory bowel disease and what diseases does it include?
collective term that refers to chronic inflammation of the lower GIT
Crohn’s Disease
Ulcerative Colitis
what are potential causes of inflammatory bowel disease?
altered epithelial barrier integrity
changes to microbial quorum
gut brain interactions (e.g. cortisol released via stress mechanisms)
what is Crohn’s disease?
chronic inflammatory condition
damage to epithelium and high levels of uncontrolled inflammation
what complications can Crohn’s disease lead to?
changes to bowel epithelium –> scarring –> bowel obstruction
mouth and perineum ulcers
fistulas
what area does Crohn’s disease normally affect?
small bowel
what are active disease symptoms of Crohn’s disease?
diarrhoea abdominal pain fatigue fever blood in stool
how is Crohn’s diagnosed?
fecal calprotectin
colonoscopy - most definitive method of diagnosis
how is crohn’s treated?
Paediatric; enteral nutrition for 4 weeks
Adult: Corticosteroids, Azathioprine & mercaptopurine – commonly used IBD immunosuppressant
Biological therapies – antibodies that neutralise TNF
what is ulcerative colitis?
chronic inflammatory condition restricted to the colon
Damage to colonic epithelium leading to ulcer-like appearance of mucosa
what can ulcerative colitis lead to?
perforation of the colon severe bleeding dehydration systemic inflammation colon cancer
what are the active disease symptoms of ulcerative colitis?
bloody diarrhoea urgency abdominal pain fatigue fever weight loss
how is ulcerative colitis diagnosed?
feral calprotectin
colonoscopy
how is ulcerative colitis treated?
Mild/moderate; 5-ASAs – oral, suppository or enema
Severe symptoms; biological therapies, ciclosporin
Surgery (colectomy) - remove diseased colon suffering from severe damage caused by long-term inflammation
what is the cause of IBS?
unknown
what is IBS?
umbrella term for FGIDS (functional gastrointestinal diseases) where pathophysiology is unknown but with a defined set of symptoms
in IBS, if the FGID occurs in the upper GIT, what symptoms are seen?
functional GERD, functional dyspepsia, bloating, pain
in IBS, if the FGID occurs in the lower GIT, what symptoms are seen?
abdominal pain, cramping, constipation and diarrhoea
how is IBS diagnosed?
ROME IV questionnaire after other causes excluded e.g. IBD, anemia, gastroenteritis
how is IBS treated?
dietary control - FODMAP diet or removing triggers
treating specific symptoms - laxatives for constipation, diarrhoea with loperamide
specific IBS treatments
name and explain some of the specific IBS treatments
Linaclotide: increase fluid secretion and pain relief
Lubiprostone: increase fluid secretion
Rifaximin: antibiotic to treat bacterial overgrowth
