SN7
SHORT NOTE
5M
★ High-yield
Write a short note on peptic ulcer.
Definition
Peptic ulcer = a breach in the mucosa of the stomach or duodenum extending through the muscularis mucosae, produced by the digestive action of acid and pepsin.
Pathogenesis — Imbalance of Factors
| Aggressive factors | Defensive factors |
|---|---|
| Acid and pepsin | Mucus–bicarbonate barrier |
| Helicobacter pylori | Prostaglandins (PGE2) |
| NSAIDs and aspirin | Mucosal blood flow |
| Smoking, alcohol | Rapid epithelial turnover (3–5 days) |
| Stress, steroids | Tight junctions |
Role of Helicobacter Pylori
- A Gram-negative spiral organism, found in 90% of duodenal and 70% of gastric ulcers
- Survives the acid by producing urease, which splits urea to ammonia and creates an alkaline microenvironment
- Causes antral gastritis → damages D cells → ↓ somatostatin → ↑ gastrin → ↑ acid
- Detected by urea breath test, rapid urease test, stool antigen, biopsy
- Classified by WHO as a class I carcinogen — predisposes to gastric carcinoma and malt lymphoma
Gastric VS Duodenal Ulcer
| Feature | Gastric ulcer | Duodenal ulcer |
|---|---|---|
| Acid secretion | Normal or low | High |
| Chief defect | Weak mucosal defence | Excess acid |
| Pain timing | Worse with food | Relieved BY food; pain 2–3 h after meals and at night |
| Weight | Loss (afraid to eat) | Gain or unchanged |
| Malignant potential | Present — must biopsy | Virtually never |
Complications
- Haemorrhage — the commonest; haematemesis and melaena
- Perforation — sudden severe pain, board-like rigidity, gas under the diaphragm
- Gastric outlet obstruction from scarring → vomiting, succussion splash
- Malignant change — gastric ulcers only
Applied Aspects
- Proton pump inhibitors block the final common pathway (H+–K+ ATPase) — the most effective acid suppressants
- Triple therapy — PPI + amoxicillin + clarithromycin for 14 days eradicates H. Pylori and largely prevents recurrence
- Misoprostol, a PGE1 analogue, prevents NSAID-induced ulcers by replacing the missing prostaglandin
- Stress (Curling) ulcers after burns; Cushing ulcers with head injury — both from mucosal ischaemia
All questions in Gastrointestinal System
- Q1Describe the composition and functions of gastric juice. Explain the mechanism of hydrochloric acid secretion and the phases of gastric secretion. ★
- Q2Describe the composition and functions of pancreatic juice. Explain the activation of its enzymes and the regulation of its secretion. ★
- Q3Describe the composition and functions of bile. Explain the enterohepatic circulation of bile salts and the functions of the gall bladder. ★
- Q4Describe the digestion and absorption of carbohydrates, proteins and fats in the gastrointestinal tract. ★
- Q5Describe the movements of the gastrointestinal tract. Explain the law of the gut and the migrating motor complex. ★
- SN1Describe the composition, functions and regulation of saliva. ★
- SN2Describe the stages and mechanism of deglutition. ★
- SN3Describe the mechanism of vomiting and the effects of persistent vomiting. ★
- SN4Enumerate the gastrointestinal hormones. Give their sources, stimuli and actions. ★
- SN5Enumerate the functions of the liver. ★
- SN6Describe the factors regulating gastric emptying.
- SN7Write a short note on peptic ulcer. ★