1. PATHOPHYSIOLOGY

2. NSAID use COX-1 inhibition ↓prostaglandins in the gastric mucosa ↓mucin secretion ↓HCO3 secretion ↑HCl secretion ↓epithelial cell proliferation ↓mucosal blood flow Migrate across the lipid membrane of epithelial cells Ion trapping Direct epithelial cell toxicity Impairment of mucosal defense system

3. Disruption of mucosal integrity ULCERATION Ulcer burrow deeper into the gastric mucosa Injury to the blood vessels GI BLEEDING Melena Coffe-ground emesis Inhibition of TXA 2 ↓platelet aggregation NSAID use