"Stomach" - what is it, definition of the term
The gastric organ, also termed the gastric chamber, is a muscular sac situated in the upper abdomen of mammals, including rodents such as rats and mice. It serves as a temporary reservoir for ingested material, where mechanical mixing and enzymatic digestion initiate. The inner lining secretes hydrochloric acid and pepsinogen, establishing an acidic environment that denatures proteins and activates pepsin for proteolysis. Muscular layers generate peristaltic contractions that propel chyme toward the small intestine. In rodents, this cavity displays a relatively simple glandular architecture compared with larger mammals, reflecting rapid digestive turnover.
Detailed information
The gastric organ of rodents is a muscular sac positioned between the esophagus and the duodenum. Its primary function is to store ingested material, mix it with gastric secretions, and regulate the rate of entry into the small intestine.
In rats, the organ exhibits a pronounced fundus and a relatively large capacity compared to mice. Mice display a shorter corpus and a less distensible fundic region. These morphological distinctions influence the volume of food that can be accommodated during a single meal.
Histologically, the wall consists of four layers:
- mucosa: simple columnar epithelium with gastric pits and chief cells
- submucosa: loose connective tissue containing blood vessels and nerves
- muscularis externa: inner circular and outer longitudinal smooth‑muscle layers
- serosa: thin connective tissue covering
Gastric glands secrete hydrochloric acid, pepsinogen, intrinsic factor, and mucus. Acidic pH in the lumen typically ranges from 2.5 to 3.5 in rats and 3.0 to 4.0 in mice, reflecting species‑specific regulatory mechanisms.
Key functional parameters:
- gastric emptying half‑time: approximately 30 min in rats, 20 min in mice
- pepsin activity peak: 1–2 h post‑feeding
- mucosal turnover rate: 3–4 days for epithelial cells
«The gastric organ of rodents serves as a critical interface between ingestion and intestinal digestion, integrating mechanical, chemical, and hormonal signals to optimize nutrient breakdown».