Gastric Physiology
Gastric physiology is the study of how the stomach receives, stores, mixes, chemically processes, and progressively releases ingested food. The stomach combines a powerful secretory function — producing acid, the protease precursor pepsinogen, intrinsic factor, mucus, and several hormones — with a motor function that triturates solids and meters their delivery to the duodenum. This area orients the more detailed topics that follow on acid secretion, the cells that produce gastric juice, motility, and the pyloric gatekeeper.
Definition
Gastric physiology is the branch of gastrointestinal physiology concerned with the normal secretory, motor, and endocrine functions of the stomach, including the production of gastric juice and the controlled mixing and emptying of gastric contents.
Scope
The area covers the secretory and motor work of the stomach as an integrated organ: the composition and control of gastric juice; the principal epithelial cell types of the oxyntic and pyloric mucosa; the electrical and mechanical basis of gastric mixing and emptying; and the role of the pylorus in regulating outflow. It is a reference orientation to normal function and does not provide diagnostic or treatment guidance.
Sub-topics
Core questions
- How is gastric juice produced and how is its secretion regulated across the cephalic, gastric, and intestinal phases?
- Which gastric cell types generate acid, pepsinogen, mucus, intrinsic factor, and regulatory peptides?
- How does gastric motor activity grind solids and control the rate of delivery to the small intestine?
- How does the pylorus coordinate with antral and duodenal activity to regulate gastric emptying?
Key concepts
- Gastric juice (acid, pepsinogen, mucus, intrinsic factor)
- Oxyntic (fundic) and pyloric mucosa
- Cephalic, gastric, and intestinal phases of secretion
- Receptive relaxation and gastric accommodation
- Antral trituration and the gastric pacemaker
- Gastric emptying and feedback from the duodenum
- Mucosal protection and the gastric mucosal barrier
Mechanisms
The stomach functions as a reservoir and processor. On the secretory side, parietal cells of the oxyntic mucosa pump hydrogen ions into the lumen via the H+/K+-ATPase, driven by histamine, gastrin, and vagal acetylcholine and restrained by somatostatin, while chief cells secrete pepsinogen that is activated to pepsin at low pH; surface and mucous-neck cells secrete the protective bicarbonate-rich mucus layer, and parietal cells also supply intrinsic factor for vitamin B12 absorption. On the motor side, a pacemaker region in the proximal stomach sets a slow-wave rhythm conducted by interstitial cells of Cajal, so that antral contractions grind solids against a closed pylorus and propel suspended particles forward; the rate of emptying is matched to duodenal capacity by nutrient- and acid-sensitive feedback. These secretory and motor processes are coordinated through neural (vagal and enteric) and endocrine signals.
Clinical relevance
Understanding normal gastric secretion, motility, and emptying provides the reference baseline against which acid-related, motility, and absorptive disorders are interpreted in the health sciences. This entry describes physiology to support comprehension and appraisal; it is not a basis for individual diagnosis or treatment.
Evidence & guidelines
The material in this area rests on classic physiological experiments and on review syntheses of gastric secretory and motor control; it is reference-educational rather than tied to clinical practice guidelines.
History
Knowledge of gastric function grew from nineteenth-century observations of a gastric fistula by William Beaumont, through Pavlov's work on neural control of secretion, to twentieth-century identification of the parietal-cell proton pump and the interstitial cells of Cajal as the gastric pacemaker. Quantitative study of gastric emptying, exemplified by Hunt and Stubbs, established that the stomach meters nutrient delivery to the duodenum.
Key figures
- Mitchell Schubert
- John G. Forte
- Kenton M. Sanders
- John N. Hunt
Related topics
Seminal works
- schubert-2008
- yao-forte-2003
- sanders-2006
- hunt-stubbs-1975
Frequently asked questions
- What is gastric juice made of?
- Gastric juice is the secretion of the stomach: it contains hydrochloric acid and intrinsic factor from parietal cells, pepsinogen from chief cells, mucus and bicarbonate from surface and mucous-neck cells, plus water and electrolytes.
- What are the two main jobs of the stomach?
- Secretion — producing acid, enzymes, mucus, intrinsic factor, and hormones — and motility — storing a meal, grinding solids, and metering their release into the duodenum.