Final answer:
The mucosal barrier of the stomach is composed of a bicarbonate-rich mucus layer, epithelial cells with tight junctions, and a quick cell turnover rate by stem cells. This barrier can break down due to NSAID use or H. pylori infection, leading to ulcers.
Step-by-step explanation:
The mucosal barrier is crucial for protecting the stomach lining from the highly acidic gastric juice. It is comprised of three main factors:
- A thick coating of bicarbonate-rich mucus, forming a physical barrier that neutralizes acid.
- Epithelial cells with tight junctions to prevent gastric juice from penetrating underlying tissues.
- Stem cells that promptly replace damaged epithelial mucosal cells, with the stomach surface being replaced every 3 to 6 days.
However, this barrier can break down, leading to ulcers. This is typically caused by the excessive intake of NSAIDs, like aspirin, or an infection by Helicobacter pylori, which disturbs the protective mechanisms.