stomach and gastric wall
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- The stomach is a muscular j-shaped organ. and is located in the upper left quadrant of the abdominal-pelvic cavity. It receives food from the esophagus. 4 main functions:
- Temporary storage of food
- mechanical breakdown of ingested food
- breakdown of chemical bonds items through the action of acids and enzymes
- production of intrinsic factor, a compound necessary necessary for the absorption of vitamin B12.
- Gastric Wall - The stomach is lined by a simple columnar epithelium dominated by mucous cells.
- Regulation of Gastric Activity ( 3 phases)
- The sight and smell, taste or thought of food initiates the cephalic phase of gastric secretion. This stage which is directed by the CNS prepares the stomach to receive food.
- Gastric Phase: This phase begins with the arrival of food in the stomach. The stimulation of stretch receptors in the stomach wall and of chemoreceptors in the mucosa triggers local reflexes controlled by the submucosal and myenteric plexuses.
- Intestinal Phase - the intestinal phase begins when chyme first enters the small intestine.
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- 4 Major layers of the Digestive tract: (Innermost to outermost)
- Mucosa: Inner lining of the digestive tract, and is an example of the mucous membrane. It consists of mucosal epithelium and an underlying of loose connective tissue. It’s thrown in fold to increase surface area available for absorption and to permit expansion after a large meal.
- Submucosa: Second layer of loose connective tissue that is deep to the muscularis mucosae. Contains large blood vessels and lymphatic vessels, as well as nerve fibers. Controls coordination of contractions of the smooth muscle layers and to regulate secretion of the digestive tract.
- Muscularis Externa: Band of smooth muscle cells arranged in an inner circular layer and the outer longitudinal layer. These actions are autonomic reflex movements controlled by another network of nerves. The parasynthetic stimulation increases muscular tone and activity whereas sympathetic stimulation promotes muscular inhibition and relaxation.
- 4 Major layers of the Digestive tract: (Innermost to outermost)