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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.
Chyme or chymus (/ k aɪ m /; from Greek χυμός khymos, "juice" [1] [2]) is the semi-fluid mass of partly digested food that is expelled by the stomach, through the pyloric valve, into the duodenum [3] (the beginning of the small intestine). [4]
The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. [3] The GI tract includes all structures between the mouth and the anus , [ 4 ] forming a continuous passageway that includes the main organs of digestion, namely, the stomach , small intestine ...
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 pH of the secreted fluid can fall by 0.8. Gastrin primarily induces acid-secretion indirectly, increasing histamine synthesis in ECL cells, which in turn signal parietal cells via histamine release and H 2 stimulation. [6] Gastrin itself has no effect on the maximum histamine-stimulated gastric acid secretion. [7]
A G cell or gastrin cell is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas [1] and duodenum. The vagus nerve innervates the G cells.
Gastric secretion at this phase rises to 40% of maximum rate. Acidity in the stomach is not buffered by food at this point and thus acts to inhibit parietal (secretes acid) and G cell (secretes gastrin) activity via D cell secretion of somatostatin. The gastric phase takes 3 to 4 hours.