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The gastrointestinal wall of the gastrointestinal tract is made up of four layers of specialised tissue. From the inner cavity of the gut (the lumen) outwards, these are the mucosa, the submucosa, the muscular layer and the serosa or adventitia.
H + is pumped into the stomach by exchanging it with K +. This process also requires ATP as a source of energy; however, Cl − then follows the positive charge in the H + through an open apical channel protein. HCO 3 − secretion occurs to neutralize the acid secretions that make their way into the duodenum of the small intestine.
The stomach is a distensible organ and can normally expand to hold about one litre of food. [22] This expansion is enabled by a series of gastric folds in the inner walls of the stomach. The stomach of a newborn baby will only be able to expand to retain about 30 ml.
The duodenum contains Brunner's glands which produce a mucus-rich alkaline secretion containing bicarbonate. These secretions, in combination with bicarbonate from the pancreas, neutralize the stomach acids contained in the chyme. Jejunum: This is the midsection of the small intestine, connecting the duodenum to the ileum.
Their secretions make up the digestive gastric juice. The gastric glands open into gastric pits in the mucosa. The gastric mucosa is covered in surface mucous cells that produce the mucus necessary to protect the stomach's epithelial lining from gastric acid secreted by parietal cells in the glands, and from pepsin, a secreted digestive enzyme ...
The gastric folds (or gastric rugae) are coiled sections of tissue that exist in the mucosal and submucosal layers of the stomach. [1] They provide elasticity by allowing the stomach to expand when a bolus enters it. These folds stretch outward through the action of mechanoreceptors, which respond to the increase in pressure. [2]
The stomach is involved in the gastric phase of digestion, following the cephalic phase in which the sight and smell of food and the act of chewing are stimuli. In the stomach a chemical breakdown of food takes place by means of secreted digestive enzymes and gastric acid. The stomach is located between the esophagus and the small intestine.
It appears rounded and is often covered by a fold on the uppermost side of the papilla; that is, the side which receives contents from the stomach. [4] The major duodenal papilla is seen from the duodenum as lying within a mucosal fold. The minor duodenal papilla is situated 2 cm proximal. [2]