Gut Health Flashcards
what is the role of the GI tract
- Intake of food e.g. nutrients, for energy
- Absorption of water
- Removal of waste (by-products of digestion, indigestible components e.g. fibre, bacterial fermentation)
where does sugar fat and protein digestion occur
- Sugar breakdown and absorption occurs in the oral cavity quickly and rapidly
- Fat is absorbed in the stomach from enzymes that come in the gallbladder
- Proteins digestion happens in the stomach
- Small intestine and large intestine breakdown all the remaining fat sugars and proteins
sugar, fat and protein digestion occurs in ,,,
different regions
what are the three parts that are used in digestion
- enzyme
- stomach acid
- proteins
what are the enzymes used in digestion
- Mouth - amylase secreted in saliva
- Stomach - pepsin
- Pancreas - trysin, amylases & lipases
how much gastric acid is produced a day
2L day is produced
what is the stomach acid made out of
- made out of gastric juice within gastric juice there is - HCL - Salts - Pepsin - Mucus - water - intrinsic factor - bicarbonate
what does the mucus do in the stomach acid
forms a gel layer over gastric epithelium this protects the epithelium and acts as a barrier preventing the breakdown of the cells in the gastric epithelium
what is the intrinsic factor used in the stomach acid
critical for B12 absorption
what does the bicarbonate do in the stomach acid
maintains pH7 at gastric epithelium with mucosal gel
what is the role of bile salts in digestion
- Secreted from hepatocytes and stored in gall bladder
- Promotes emulsification of fat into droplets – this means they turn large droplets of fats into nano droplets of fats
how much water goes into the
- stomach
- small intestine
- large intestine
- In the stomach – lot of water required for hydrolysis, therefore 2L per day goes into the stomach
- In small intestine 8L of water is absorbed
- In the large intestine 0.5L of water is absorbed
how many enteric neurones re there
400-600
where is the enteric nervous system
- it is within the GI tract
- extensors from the oesophagus to the rectum
describe the enteric nerve connection to the vagus nerve
- Vagal pathway – critical for digestion, motility and important for mechanisms such as pain
- There is a connection between the GI tract and the brain via the vagus
what is the role of the enteric nervous system
- Motility
- Nutrient uptake
- Hormone and enzyme release
- Appetite regulation
- Vascular flow
- Immune cell activity – there is an neuroimmune communication, neuropeptide released from neurons can drive inflammation
what is intrinsic innervation
this is communication within the gut
- - They do not communicate with other neurones outside the gut for example they do not communicate with neurones in the CNS
describe intrinsic innervation
- Between the two longitudinal muscles and circular muscles is the myenteric plexus
- The submucosal plexus is located beneath the mucosa, the submucosal plexus has a different role due to its location, it is very highly dense
- The mucosa is in communication with epithelial cells
what is the role of the myenteric plexus
this is involved in contraction and relaxation
what is the role of the submucosal plexus
involved in outside world such as regulating the microbiota, involved in secretion and nutrient uptake
what are the two plexuses in the intrinsic nervous system
myenteric and submucosal
what do interneurones do
- Interneurons allow connectivity between different type of neurones,
- There are neurones between circular muslces and longitudinal muscles
- Communication and co-ordination between neurones critical for normal GIT function
what is the extrinsic innervation of the gut
vagus nerve mediated communication between gut and CNS
what are the two innervations of the gut
- intrinsic and extrinsic
the vagus nerve is the….
longest cranial nerve
describe the vagus nerve and the gut
- the vagus nerve is How the gut and the brain communicate
- Innervates GIT from mouth to transverse colon, it does not go all the way to the sigmoid and the rectum
- Innervates 2/3 of the colon
- Central terminals enter brain stem and synapse to neurones of the NTS (nuclesus tracturs solitarus)
what does the autonomic nervous system do in the gut
- Pain, digestion, secretions is what the autonomic nervous system does
what does the sympathetic nervous system do to the gut
prepares body for stressful responses (increases HR, release stored energy and decrease digestion)
what are the sympathetic ganglion that innervate the gut
– Celiac, Superior Mesenteric, Inferior Mesenteric ganglion
what is the pelvic nerve
- Pelvic nerve innervates lower part of the colon, important for parasympathetic
describe the gut microbiota
Largest microbial colony found in the colon
- it is critical in maintaining normal health as well as gut health
what diseases is the gut microbiota linked to
- Linked with obesity, inflammation and neurodegeneration
different strains of microbiota…
can be dominant depending on diet
what is decreased diversity within the microbiota associated with
- poor health
- diverse microbiota is therefore critical for good health
what do the microbiota communicate with
- they communicate with the gut epithelium
changing gut microbiota…
can chain brain microbiota which can lead to neurodegenerative diseases
how does the gut microbiota chain brain microbiota
- it can change the immune system
- - The Vagus nerve can respond to the microbiota environment and lead to changes in human behaviour
what does faecal microbiota transfer aim to do
- Aim to increase microbial diversity
how does feaecal microbiota work
- it uses Donors and super donors or artificially produced probiotics
- Trial data - obesity phenotype is reversed by FMT from lean individual, FMT induces remission in ulcerative colitis patients
what is faecal microbiota used in
- Only approved for treatment of C.difficile infection following failure of antibiotic therapy
describe clostridium difficile
- Change stop the microbiome
- Found in 2-5% of the population and causes no symptoms
what is clostridium difficile associated with
- Associated with broad spectrum antibiotic usage, opportunistic over-growth
what are the symptoms of clostridium difficile
- Causes water diarrhoea and abdominal pain
what is the treatment of clostridium difficile
- Stop antibiotic use
- Vancomycin or metronidazole
- FMT (faecal microbiota transfer)
what do probiotics do
- Prebiotics promote growth and survival of bacteria (and fungi)
- Stimulates production of Bifidobacterium & Lactobacillus
what are probiotics presence in
• Non-digestible food ingredients
– Fructans
– Galactans
– Dietary fibres (inulin – asparagus, leek)
- Probiotics are live cultures found in dairy products (e.g. yogurt) or fermented foods (e.g. pickled vegetables and soy products)
how is probiotics used for gut health
- Role in maintaining normal microbial quorum required for healthy epithelium, ENS and immune cell activity
what are common GI conditions
- Abdominal pain, discomfort, bloating, constipation and gastroenteritis
- Upper GI symptoms: acid reflux, nausea, vomiting, belching, gastroparesis and bloating
- Lower GI symptoms: bloating, constipation, diarrhoea, abdominal pain
how is Gastroesophageal reflux disease caused
- Movement of stomach contents from the fundus into the distal oesophagus
- Lower esophageal spinchter(LOS) is relaxed allowing passage of acid into the lower oesophagus
- LOS is anatomical valve – usually closed
- LOS is weaker and relaxed it causes symptoms of GERD
How is Gastroesophageal reflux disease treated
Treated first with:
- OTC (antacids + alginates e.g. Gaviscon) produced protective layer over lumen
Prescription treatments:
- Proton Pump Inhibitors (block stomach acid production)
what are the symptoms of Gastroesophageal reflux disease
- Commonly associated with weight gain, gastroparesis and stress
- Chronic condition that can lead to ulcer formation, inflammation and Barratt’s esophagus
- Diagnosed usually by symptoms
what is gastroparesis
- Chronic condition that is characterised by delayed gastric emptying
- Diabetic gastroparesis caused by neuropathy (damage to the neuroens)of vagal endings innervating the stomach
what are the symptoms of gastroparesis
- Symptoms include nausea, vomiting, rapid feeling of fullness, reflux, pain and bloating
- Can lead to malnutrition (fill full quickly even though your not eating very much), formation of bezoars (hardened mass of undigested food), changes to blood sugar
how do you diagnose Gastroparesis
- Use a gastric emptying study
- Pateitn given a meal C13 labeled meal is ingested
- Released C13 is exhaled in breath and is used as marker of food movement through stomach
- Time-course compared to normal values
how do you treat Gastroparesis
- Domperidone or erythromycin: stimulate stomach muscle contraction to help move the food through
- Anti-emetics for nausea
- Dietary changes e.g. smaller, more frequent meals, soft foods
what are the two conditions that make up IBS
Crohn’s disease and ulcerative colitis
what is the cause of IBS
- Unknown cause – could be due to altered epithelial barrier integrity (leaky epithelium allowing pathogens through), changes to microbial quorum, gut-brain interactions e.g. cortisol released via stress mechanisms.
describe Crohn’s disease
- Chronic inflammatory condition that affects the whole of the GIT but is associated and often localised to the small bowel
- Can be ileocolonic, colonic and ileum depending on area that is involved
- Damage to epithelium and high levels of uncontrolled inflammation
what are the symptoms of Crohn’s disease
- Diarrhoea
- Abdominal pain
- Fatigue
- Fever
- Blood in stool
what does Crohn’s disease lead to
- Changes to bowel epithelium resulting in scarring
- Scarring and changes to epithelium can can bowel obstruction (can be fatal if untreated)
- Ulcers (in mouth and perineum)
- Fistulas (significant damage causing a ‘hole’ in bowel)
how do you diagnose Crohn’s disease
- Fecal calprotectin (>250μg/g)
- Colonscopy (assess area and degree of inflammation)
what is the paediatric treatment for Crohn’s disease
- Enteral nutrition for 4 weeks uses modulen
- Replaces normal diet with a drink that contains all the nutrients that a child will drink
- Promotes epithelial healing without side-effects of steroids (steroids can stunt growth)
what is the adult treatment for Crohn’s disease
- Corticosteroids - Prednisolone, Budenoside (short-term)
- Azathioprine & mercaptopurine – commonly used IBD immunosuppressant
- Biological therapies – antibodies that neutralise TNF (e.g. Infliximab, adalimumab)
describe Ulcerative colitis
- Chronic inflammatory condition that is restricted to the colon
- Damage to colonic epithelium leading to ulcer-like appearance of mucosa
what are the symptoms of Ulcerative colitis
- Bloody diarrhoea
- Urgency
- Abdominal pain
- Fatigue
- Fever
- Weight loss
what can Ulcerative colitis lead to
- Perforation of the colon (can be fatal)
- Severe bleeding
- Dehydration
- Systemic inflammation
- Colon cancer
how is Ulcerative colitis diagnosed
- Fecal calprotectin (>250μg/g)
- Colonscopy (assess area and degrees of inflammation)
How is Ulcerative colitis treated
Mild/Moderate symptoms:
- 5-ASAs : Aminosalicylates (sulphasalazine, mesalazine) – these can be Oral, suppository or enema, this depends on ergency and where the inflammation is
- Corticosteroids - Prednisolone
Severe symptoms:
- Biological therapies – antibodies that neutralise TNF (e.g. Infliximab, adalimumab)
- Ciclosporin – IV
Surgery (colectomy) : remove diseased colon suffering from severe damage caused by long-term inflammation
what is IBS a umbrella term for
Functional Gastrointestinal Diseases (FGIDs) where pathophysiology is unknown but with defined set of symptoms.
what is the FGIDs in the upper GIT
functional GERD, functional dyspepsia, bloating, pain
what are the FGIDs in the lower GIT
abdominal pain, cramping, constipation and diarrohea.
how is IBS diagnosed
- IBS is diagnosed using a ROME IV questionnaire after excluding all biolgical causes e.g. IBD, anemia, gastroenteritis etc., dependent on pain
how is IBS caused by the gut brain axis
- stress
- Changes to microbiotia environment - Usually after Gastroenteritis
- Autonomic nervous system, HPS axis and the gut,
what are the causes of IBS
- Lower GIT IBS symptoms often arise after gastroenteritis
- Leaky gut epithelium?
- Change to the microbiome quorum?
- Increased sensitivity to pain (visceral hypersensitivity)
- Abnormal activity of enteric neurons leading to changes in motility (diarrohea and constipation)
what is the treatment of IBS
• Dietary control e.g. FODMAP diet – this reduces the intake of different types of sugars which elevates some symptoms
• Treat specific symptoms e.g. diarrhoea with loperamide, constipation with fibre/laxatives, anti-depressants (depression is comorbidity), pain medication (e.g. pregabalin)
• Specific IBS treatments:
– Linaclotide: increase fluid secretion and pain relief
– Lubiprostone: increase fluid secretion
– Rifaxim
