Definition
- Gastric secretion is exocrine output of gastric glands: chiefly HCl, pepsinogen, mucus and intrinsic factor.
- It occurs in three phases: cephalic, gastric and intestinal, contributing 30 to 50%, 50 to 60% and about 10% of gastric juice.
Composition and Functions of Gastric Secretion
Major constituents of gastric secretion
Constituent
HCl
- Secreted by
- Parietal cells, fundus and body
- Principal function
- Converts pepsinogen to pepsin; provides acidic medium for digestion
Pepsinogen
- Secreted by
- Chief cells
- Principal function
- Converted to pepsin by HCl; pepsin is a strong proteolytic enzyme
Mucus
- Secreted by
- Mucus-secreting cells, neck region of gastric glands
- Principal function
- Alkaline, HCO3--retaining layer; buffers HCl and protects mucosa from acid-peptic digestion
Intrinsic factor
- Secreted by
- Parietal cells
- Principal function
- Glycoprotein required for vitamin B12 absorption from terminal ileum