How does the stomach's lining protect itself from the acidic gastric juice it produces?
The stomach lining protects itself by building a mucosal barrier: a thick coating of bicarbonate-rich mucus, tight junctions that seal epithelial cells together, and rapid replacement of damaged surface cells by dividing stem cells.
The stomach mucosa defends against its corrosive gastric juice through what the text calls the mucosal barrier. The surface epithelium consists of mucous cells that produce a cloudy, protective two-layer coat of alkaline mucus, with a viscous, insoluble surface layer that traps a layer of bicarbonate-rich fluid underneath it. In addition, the epithelial cells are joined by tight junctions that prevent gastric juice from leaking into the underlying tissue layers. Finally, damaged epithelial cells are shed and quickly replaced through division of undifferentiated stem cells located where the gastric pits join the gastric glands; the stomach surface epithelium is completely renewed every three to six days.
Key points
- A thick coating of alkaline, bicarbonate-rich mucus is produced by surface mucous cells and forms the first layer of defense.
- Tight junctions between gastric epithelial cells block gastric juice from penetrating to deeper tissue layers.
- Damaged surface epithelial cells are shed and replaced rapidly by stem cell division, with full renewal every three to six days.
Related questions
- What are the three phases of gastric secretion and what triggers each phase?
- Compare the mucosa of the large intestine with that of the small intestine, and explain how the differences relate to their functions.
- What are the three structural modifications of the small intestine that increase its surface area for absorption?
- How do circular folds, villi, and microvilli contribute to the absorptive function of the small intestine?
- Describe the sequence of events in the pharyngeal-esophageal phase of swallowing, including the role of the swallowing center and the protective mechanisms that prevent food from entering the respiratory passages.
- What are the three layers of the muscularis externa in the stomach wall, and how does the oblique layer contribute to stomach function?
Anatomy Physiology by Elaine N. Marieb, Katja N. Hoehn
Elaine N. Marieb and Katja Hoehn
Sixth Edition