Stomach

Abstract

2. Mark the correct statement regarding gastric anatomy. Comments The stomach is a rather mobile organ, held in place at either end by the phrenoesophageal ligament proximally and the duodenum distally. This degree of motility allows it to rotate along its axis, creating a gastric volvulus. Gastric volvulus can be organoaxial (i.e., along the longitudinal axis or cascade volvulus along its horizontal axis). The most important predisposing factors are gastric distention and the shape of the stomach itself. Long, vertically oriented stomachs are prone to organoaxial volvulus, whereas broad horizontally oriented stomachs are predisposed to a cascade volvulus. Gastric volvulus has not been associated to gastric banding [ 3 ] (Fig. 12.1 ). Due to its mobility, the stomach is often used to replace the esophagus in the chest. In order to mobilize the stomach, the short gastric vessels, the left gastric artery, the right gastric artery, and the left gastroepiploic artery are divided. In such cases, the right gastroepiploic artery may feed the entire stomach [ 4 ].The stomach is attached to other abdominal organs through the derivatives of the ventral and dorsal mesogastria. The ventral mesogastrium forms the lesser omentum, which may harbor accessory or replaced left hepatic arteries arising from the left gastric artery. The dorsal mesentery forms the gastrosplenic ligament (which encases the short gastric vessels), the splenic capsule, and the splenophrenic ligament [ 5 ]. e) Intrinsic factor is produced by P cells (parietal cells).Comments Gastric acid secretion is the sole function of the parietal cells. This is a fi nely regulated process, under the infl uence of neural, hormonal, and intraluminal stimuli. Parietal cells are located exclusively in the fundus and body of the stomach, which is the basis of limiting highly selective vagotomy to the branches of the nerve of Latarjet going to this portion of the stomach. Located in the antrum, G cells, through gastrin production, are the most important positive regulators of acid secretion. They are stimulated by vagal efferents as well as by the presence of food in the gastric lumen. Gastrin reaches the oxyntic region of the stomach (fundus and body), where it stimulates the production of acid by parietal cells directly and indirectly, by inducing histamine release from enterochromaffi n-like cells. The acidifi cation of the gastric lumen stimulates somatostatin-producing D cells in the antrum, which inhibit G cells in a paracrine manner.Interestingly D cells are also found in the oxyntic region of the stomach; however, in this location, they lack luminal receptors and do not respond to gastric acidifi cation. Instead, they respond to the hormones released by duodenal acidifi cation, namely, CCK, secretin, and gastric inhibitory peptide, and further downregulate gastric production.M cells produce mucus. While they are located throughout the stomach, they are most abundant in the antrum. Chief cells share their location with parietal cells. They produce intrinsic factor,...