Describe the phases of gastric secretion and explain NSAID-induced ulcers and stomach autodigestion prevention.

Here are the answers to your questions:

a. Mention the phases of gastric secretion
The three phases of gastric secretion are:

• Cephalic phase
• Gastric phase
• Intestinal phase

D. Explain briefly why a person who takes NSAIDS orally, is likely to develop ulcers in the stomach
NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) inhibit the production of prostaglandins by blocking the enzyme cyclooxygenase (COX). Prostaglandins are essential for maintaining the stomach's protective mucosal barrier by stimulating mucus and bicarbonate secretion and promoting mucosal blood flow. When prostaglandins are inhibited, this protective barrier weakens, making the stomach lining vulnerable to damage from gastric acid and digestive enzymes, leading to ulcer formation.

E. Explain autodigestion of the stomach and how this is prevented

• Autodigestion: This refers to the stomach digesting its own walls. The stomach produces highly acidic gastric juice (hydrochloric acid) and powerful proteolytic enzymes (like pepsin) to break down food. Without protective mechanisms, these substances could damage and digest the stomach's own tissues.
• Prevention: The stomach is protected by the gastric mucosal barrier, which includes:
  • A thick layer of alkaline mucus that coats the stomach lining, providing a physical and chemical barrier.
  • Bicarbonate ions trapped within the mucus layer, which neutralize acid that penetrates the mucus.
  • Tight junctions between epithelial cells, preventing gastric juice from seeping between cells.
  • Rapid epithelial cell turnover, allowing damaged cells to be quickly replaced.
  • Adequate mucosal blood flow, which helps remove acid and supply nutrients for repair.