Stomach and duodenum Flashcards
Name 4 ways of determining a subject’s H. Pylori status?
1) Breath test. 2)Gastric biopsy. 3) Serum test. 4)Stool antigen
What are the 2 main causes of peptic ulcers?
NSAIDs and Helicobacter Pylori
What are the 3 stages of digestion?
1) Cephalic 2) Gastric 3) Intestinal
What normally prevents gastric acid from refluxing into the oesophagus?
Lower oesophageal sphincter
What is the normal resting pressure of the lower oesophageal sphincter and how do we measure that?
Approximately 30mmHg, measured using manometry.
Why does acid cause damage to the oesophageal mucosa but not to the gastric mucosa?
The oesophagus is squamous cells that are sensitive to acid. The stomach/gastric mucosa is columnar cells which protect against acid.
What is Barrett’s oesophagus?
Pre-malignant changes in the oesophagus. 0.5% chance per annum of contracting cancer. Treat using acid suppression and regular endoscopes.
What is Nissen fundoplication?
An invasive surgical procedure used to treat reflux disease. It causes dysphagia for weeks, normally wears off but is persistent in around 3% of patients. Patients who have it can’t burp which leads to gas bloating.
How do histamine 2 receptor antagonists work?
ECL cells release histamine which binds to histamine 2 receptors on parietal cells which causes the release of gastric acid. H2r antagonists competitively inhibits the histamine 2 receptor on parietal cells so less acid is secreted.
Name two histamine 2 receptor antagonists and state by what percentage they decrease gastric acid secretion.
- Cimetidine (Tagamet)
- Rantidine (Zantac)
- They reduce gastric acid secretion by approx. 60% but if used long term their inhibitory efficacy is reduced.
How long do PPIs inhibit acid for after a single dose?
24-48 hours.
By what percentage do PPIs inhibit gastric acid secretion?
90% or more.
How do PPIs avoid being activated in the stomach?
They have a special coating on them which prevents them being activated the gastric mucosa and so allows it to travel in the systemic circulation to the proton pump/
When should PPIs be taken and why is this important?
Approx. 30 minutes before a meal. This is done so that the meal will be stimulating the activity of the proton pump at a time when the proton pump inhibitor is active. This is important as the drug is only active against activated proton pumps.
What is the treatment for H. pylori infection?
A triple therapy involving a PPI and 2/3 of the following antibiotics: amoxycillin, clarithromycin and metronidazole. Taken for a week and eliminates 80% of infections.
How do you treat peptic ulcers caused by NSAIDs?
Stop the NSAID and heal with a PPI. Selective cox-II inhibitors have slightly less risk than non-selective NSAIDs. Occasionally, prostaglandin analogues such as Misoprostil (Cytotec) may be used along with NSAIDs to reduce their mucosal ulceration.
What type of epithelium is found in places where there is friction?
Stratified squamous epithelium.
What is atrophic gastritis?
A process of chronic inflammation of the stomach mucosa, leading to loss of gastric glandular cells and their replacement by intestinal and fibrous tissues.
What is gastro-oesophageal reflux disease?
Retrograde passage of acidic gastric contents into oesophagus. Symptoms include: heartburn, regurgitation, dyspepsia, nausea and more.
What is the angle of His?
Acute angle created between the cardia of the stomach and the oesophagus that prevents reflux.
What is a hiatus hernia?
Protrusion of part of the stomach through the diaphragmatic hiatus and into the chest. Two types: sliding (80%): gastro-oesophageal junction slides through hiatus. Rolling: fundus of the stomach protrudes through hiatus alongside gastro-oesophageal junction.
How do prokinetics works?
They increase gastric emptying and increase lower oesophageal pressure. eg. Metoclopramide.
What is tachyphlaxis?
A rapid decrease in the response to a drug due to previous (long-term) exposure to that drug.
What is a Curling’s ulcer?
A type of stress ulcer, an acute gastric erosion resulting as a complication from severe burns when reduced plasma volume leads to ischemia and cell necrosis (sloughing) of the gastric mucosa.
