Upper GI Tract Disorders Flashcards
What is included in the foregut?
- distal oesophagus to 2nd part of duodenum
What is included in the midgut?
- 3rd part of duodenum to 2/3 of transverse colon
What is included in the hindgut?
- 3rd part of transverse colon to rectum
What are the main arteries that supply the foregut, midgut and hindgut?
- foregut = coeliac artery
- midgut = superior mesenteric artery
- hindgut = inferior mesenteric artery
What are the 2 main features of swallowing?
- deliver food bolus to stomach
- protect airway from aspiration of food into lung
What is dysphagia?
- general term for swallowing difficulties
Which aspect of the oesophagus is responsible for stopping acid going back up the oesophagus?
- lower oesophagus sphincter
Which cells in the stomach secrete HCl?
- parietal cells
What is the primary protein channel in the membrane of parietal cells that is responsible for creating acid in the stomach?
- H+ / K+ ATPase is the proton pump of the stomach
Is the stomach function generally controlled by the sympathetic or parasympathetic nervous system?
- parasympathetic
What are the 3 ways in which parietal cells secrete HCl?
1 - ACh from vagus nerve (Gaq)
2 - Gastrin (Gaq)
3 - Histamine (Gas) due to gastrin stimulation
What is the direct and indirect action of gastrin on stimulating parietal cells to secrete gastric juice?
- direct = gastrin stimulates parietal cells directly
- indirect = gastrin stimulates histamine release that stimulates parietal cells
Gastrin is able to stimulate parietal cells both directly and indirectly, what type of cell signalling is the direct and indirection action of gastrin on stimulation parietal cells?
- direct = endocrine
- indirect = paracrine (nearby cells)
ACh, gastrin and histamine all work on different receptors on parietal cells, which receptors are present on parietal cells for each of the stimulus?
- ACh = Gaq and ⬆️ Ca2+
- gastrin = Gaq and ⬆️ Ca2+
- histamine = Gas and ⬆️ cAMP and phosphokinase A
What is gastro-oesophageal reflux disease (GORD)?
- leakage of acid from stomach into oesophagus
What are the main cuases of gastro-oesophageal reflux disease (GORD)?
- failure of the lower oesophageal sphincter to close fully
- temporary relaxations of the lower oesophageal sphincter
- failure of the diaphragmatic sphincter
- hiatal hernia
- increased intra-abdominal pressure
How common is gastro-oesophageal reflux disease (GORD)?
- very common
- 20-30% in western world will have regular GORD
- 50% of people will have at least one case of GORD
What is the most common bacterial infection that is a risk factor for Gastro-oesophageal reflux disease (GORD)?
- helicobacter pylori
What are the 3 most common risk factors that can increase intrabdominal pressure and therefore the risk of developing Gastro-oesophageal reflux disease (GORD)?
- obesity
- pregnancy
- ascites
What are some of the most common lifestyle risk factors for developing Gastro-oesophageal reflux disease (GORD)?
- alcohol
- smoking
- physcial activity/exercise
- depression/anxiety
What is the one non-modifiable risk factor for developing Gastro-oesophageal reflux disease (GORD)?
- age
- older people are more at risk
Do all patients with gastro-oesophageal reflux disease (GORD) present with symptoms?
- no
- majority are asymptomatic
Of the patients who do experience gastro-oesophageal reflux disease (GORD) related symptoms, what are the 3 most common symptoms?
1 - acid reflux (”heartburn”) medical term is dyspepsia
2 - burning in chest/throat
3 - reflux of acid into mouth with sour taste
Patients with gastro-oesophageal reflux disease (GORD) may experience the globus sensation, what is this?
- a persistent sensation of a lump in the throat
Patients with gastro-oesophageal reflux disease (GORD) may experience some generic symptoms, what are the most common?
- upper abdominal or non-cardiac chest pain
- respiratory symptoms due to aspiration and bronchospasm that may be worse at night
- persistent nausea and vomiting
- poor dentition (enamel erosion on inside of teeth)
What is the most common method for diagnosing patients with suspected gastro-oesophageal reflux disease (GORD)?
- mostly clinical
When diagnosing patients with suspected gastro-oesophageal reflux disease (GORD), clinical interpretation of symptoms is the most commonly approach, however if needed an endoscopy - oesophago-gastro-duodenoscopy (OGD), can be performed, what is this?
- camera down the throat
- able to travel to upper duodenum
When diagnosing patients with suspected gastro-oesophageal reflux disease (GORD), clinical interpretation of symptoms is the most commonly approach. However if needed an endoscopy - oesophago-gastro-duodenoscopy (OGD), can also be performed, but if a patient cannot have a OGD what older methods can be used for diagnosis?
- X-ray using contrast dye (barium)
- oesophageal manometry and pH studies
- faeces or breath testing for H. pylori
Do all patients who are colonised with Helicobacter pylori (H. pylori) present with symptoms?
- no
- greater than 70% have no symptoms
Helicobacter pylori (H. pylori) is not able to live in the stomach due to the acid conditions, but what is it able to do to ensure its survival in the stomach?
- flagella help navigate to higher pH areas (fundus) and lining
- releases urease that converts urea to CO2 and ammonia
- ammonia neutrilises stomach pH
Helicobacter pylori (H. pylori) are microaerophilic, what does this mean?
- requires only a little O2
- die with high O2 levels
Some strains of Helicobacter pylori (H. pylori) are able to produce cytotoxin-associated gene A (CagA), what is this?
- a virulence factor associted oncogene
- associated with inflammation, increased risk of ulcers and cancer
All strains of Helicobacter pylori (H. pylori) are able to produce vacuolating toxin A (VacA), what is this?
- protein secreted by H. pylori
- all strains produce active VacA as need cofactors
- can causes cell damage
What are the 4 main diseases that can be causes by Helicobacter pylori (H. pylori)?
1 - gastritis (inflammation of stomach)
2 - dyspepsia (chronic acid reflux)
3 - peptic ulceration
4 - gastric cancer
Peptic ulcers are one of the main diseases that can be causes by Helicobacter pylori (H. pylori). What are the 2 most common types of ulcers?
- 70-85% gastric ulcers
- 90-95% duodenal ulcers
Gastric cancer is one of the main diseases that can be caused by Helicobacter pylori (H. pylori). What are the 2 most common types of cancer caused by H. pylori?
- adenocarcinoma (starts in mucus-producing glandular cells)
- mucosa-associated lymphoid tissue (MALT) lymphoma (92-98% cases), can also cause non-hodgkins lymphoma
In patients with gastro-oesophageal reflux disease (GORD) what lifestyle factors can they be advised to change?
- alcohol
- smoking
- diet
- weight loss
In patients with gastro-oesophageal reflux disease (GORD) what pharmacotherapies can be used?
- proton pump inhibitors
- H2 receptor antagonists
In patients with gastro-oesophageal reflux disease (GORD) proton pump inhibitors and H2 receptor antagonists can be prescribed. Do these drugs stop reflux?
- no
- they reduce acid secretion
- do not stop cause of reflux
If a patient has been diagnosed with Helicobacter pylori (H. pylori), what treatment would they be prescribed?
- “Triple therapy” 7 days – PPI plus 2 antibiotics (e.g. amoxicillin and metronidazole)
- 66% effective
- high rates of metronidazole resistance in treatment failures
Proton pump inhibitors are a drug that is used to reduce acid production in the stomach. What is the most commonly used drug that we need to be aware of called?
- omeprazole
- other drugs include lansoprazole, esomeprazole
- all end in prazole
Proton pump inhibitors are a drug that is used to reduce acid production in the stomach. Omeprazole is the most commonly used drug that we need to be aware of, what is the mechanism of action of this drug and what does it help with?
- direct permanent binding to H+/K+ ATPase (“the proton pump”)
- inhibits H+ and K+ exchnage
- significant reduces HCl secretion (>95%)
Proton pump inhibitors are a drug that is used to reduce acid production in the stomach. Omeprazole is the most commonly used drug that we need to be aware of. It is able to bind with the H+/K+ pump and inhibit the release of H+ that form HCl in the stomach. Although side effects are rare, what are the most common side effects?
- diarrhoea
- increased risk of GI infection (e.g. C. difficile)
If a patient is unable to tolerate proton pump inhibitors, what drug could be used as an alternative?
- H2 receptor antagonist
- ranitidine
- educes histamine stimulation of acid production but not gastrin of ACh