The stomach is:
Physical features of the stomach:
1. When the stomach is empty, it collapses its large longitudinal folds called rugae.
2. Food enters the stomach from the esophagus through the cardiac sphincter (gastroesophageal sphincter).
3. Chyme leaves the stomach through the pyloric sphincter into the small intestine.
4. The stomach regions are the fundus, body and pylorus.
5. The lateral surface of the stomach (convex side) is called the greater curvature. The medial surface of the stomach (concave side) is called the lesser curvature.
6. The peritoneum associated with the stomach is called the greater omentum. It comes off the greater curvature of the stomach. The lesser omentum comes off the lesser curvature of the stomach.
7. The stomach has the 4 basic tunics of the alimentary canal - the mucosa, submucosa, muscularis, serosa (except the muscular layer is modified).
a) The mucosa has 3 layers: The top layer is epithelium is all columnar cells that produce lots of mucus. It is interspersed with gastric glands that produce digestive enzymes and other *specialized secretory cells (more below) and gastric pits that sink into the deeper layers and from which flows gastric juice. The middle layer is lamina propria made of loose connective tissue, smooth muscle and lymph tissues. The deep layer is muscularis mucosa made up of smooth muscle.
b) The submucosa is dense connective tissue supporting blood vessels and lymphatic tissue.
c) The muscularis layer, which is usually just a circular and longitudinal layer in the rest of the digestive tract, has amn additional third innermost layer of smooth muscle that runs obliquely. This allows the stomach to create mixing action for breaking food down.
d) The serosa is the outer layer of the stoamch made up of serous membrane.
*Most chemical digestion occurs in the fundus and body of the stomach. The glands here have the following types of secretory cells.
After reading about stomach anatomy and studying the diagram. Take the Stomach Anatomy - Short Answer Quiz.
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Amsel, Sheri. "Stomach Anatomy (Advanced)" Exploring Nature Educational Resource ©2005-2021. October 21, 2021
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