Mucosal Barrier of the Stomach

In the gastric glands, the parietal cells are involved in hydrochloric acid or HCl formation.

These cells first synthesize carbonic acid, which dissociates into hydrogen and bicarbonate ions.

The proton pumps actively transport these hydrogen ions into the lumen.

In contrast, the bicarbonate ions are exchanged with chloride ions from the interstitial fluid, which are passively released in the lumen.

These ions combine to form HCl, which aids digestion and eliminates pathogens.

The gastric mucosa protects itself from the acid by creating a mucosal barrier. This coating protects the cells against enzymatic digestion and neutralizes harsh acids.

The tight junctions between epithelial cells further enhance the integrity of the mucosal barrier by preventing acid leakage into the underlying tissues.

Additionally, any damaged mucosal epithelium is shed and quickly replaced by the division of underlying stem cells.

Despite its robust nature, factors like Helicobacter pylori infections, non-steroidal anti-inflammatory drugs, or acid-mucus imbalance can breach the mucosal barrier, leading to ulcers.