Final answer:
The branched tubules in the stomach's lining are the gastric glands, which secrete gastric juice for digestion and an acidic mucus for protection. The mucosal barrier comprising bicarbonate-rich mucus and tight epithelial cell junctions guards the stomach against self-digestion.
Step-by-step explanation:
Gastric Glands and Mucosal Barrier in the Stomach
The inner lining of the stomach is equipped with specialized gastric glands that are responsible for the secretion of gastric juice. These glands are found at the base of gastric pits, which are small depressions in the stomach mucosa. Gastric glands are made up of various cell types, including mucous neck cells, which secrete an acidic type of mucus different from the alkaline mucus produced by surface mucus cells. The main function of gastric juice is to break down food through enzymes like pepsin, which is activated by hydrochloric acid produced by the gland's parietal cells.
The stomach's mucosal barrier plays a crucial role in protecting the organ from the highly corrosive nature of gastric juice. It is comprised of a thick coat of bicarbonate-rich mucus that neutralizes acid, tightly sealed epithelial cells, and a rapid turnover rate of these cells by underlying stem cells. This robust mucosal barrier ensures that the stomach does not digest itself and maintains the integrity of the stomach lining against damaging effects of gastric juice and chyme, preserving the motility movement of food through the gastrointestinal tract.