Stomach

• The layers of the stomach include the mucosa, submucosa, muscularis, and serosa.
• The gastric glands are described as simple, branched, tubular glands, tightly packed and extend from the bottom of the gastric pits to the muscularis mucosae.
• The histological transition at the gastroesophageal junction is described as a change from the squamous mucosa of the esophagus to the simple columnar epithelium of the stomach.
• The Digestive system includes the glands: salivary, pancreas, liver, gall bladder; the tract: esophagus, small intestine, large intestine; and the accessories: lips, pharynx, tongue.
• The general structure of the GI Tract includes the upper esophagus to lower rectum, mucosa, submucosa, muscularis, and serosa.
• The mucosa is the lining epithelium, underlying CT (lamina propria), smooth muscle (muscularis mucosae), submucosa, and muscularis.
• The fundic glands, also called gastric glands, are present throughout the entire gastric mucosa except for the region occupied by the pyloric glands.
• Proton pump inhibitors have become the treatment of choice in managing HCl hypersecretion in Zollinger-Ellison syndrome.
• Diseases of the esophagus and stomach are a significant aspect of gastric histology.
• Zollinger-Ellison syndrome, also known as gastrinomas, is a condition characterized by excess secretion of gastrin by gastrinoma of the duodenum or pancreas.
• The structure of the gastric pits and glands is a crucial aspect of gastric histology.
• Excessive secretion of hydrochloric acid by continuously stimulated parietal cells is a characteristic of Zollinger-Ellison syndrome.
• The various types of gastric gland cells include Mucus, parietal, chief, enteroendocrine, and Stem cells.
• The histologic layers of the gastric wall include Mucosa, submucosa, muscularis, and serosa.
• The fundic glands are simple, branched, tubular glands, tightly packed and extend from the bottom of the gastric pits to the muscularis mucosae.
• The isthmus of the fundic gland is a site of the stem cell's location.
• Gastric glands extend from the bottom of the gastric pits to the muscularis mucosae.
• Parietal cells are bacteriostatic, meaning some bacteria can adapt to the low pH.
• Intrinsic factor, a glycoprotein, binds to vitamin B12, which is essential for its absorption, which occurs in the distal part of the ileum.
• Direct contact with the wall of the stomach interferes with the hydrophobic properties of the gastric mucosa.
• Deficiency of intrinsic factor leads to pernicious anemia and vitamin B-12 deficiency.
• Mucus produced by surface mucous cells is high in bicarbonate and potassium, protects the epithelium from the stomach acid, and prostaglandins (PGE2) stimulate secretion of bicarbonates and increase thickness of the mucus.
• Parietal cells secrete HCl, which has a concentration of 150 - 160 mmol/L, pH (1.0 to 2.0), and initiates digestion of dietary protein by converting pepsinogen into the active pepsin.
• Mucus neck cells are present mainly clustered but also occur singly among the other cells in the necks of gastric glands, are less columnar than the surface mucous cells, and their mucus secretion is less alkaline than that of the surface epithelial mucous cells and is more soluble.
• Gastric glands contain stem cells.
• NSAIDs suppress the production of prostaglandins.
• Helicobacter pylori contains large amounts of urease, an enzyme that creates a protective basic “ammonia cloud” around the bacterium, allowing it to survive in the acid.
• Surface mucous cells line the surface and the gastric pits, have a lifespan of 3 to 5 days, and are of simple columnar epithelium with an apical mucus cup which protects the epithelium from stomach acid
• The gastric glands proper house five major cell types: Mucous cells, including the surface mucous cells and the mucous neck cells; Chief cells, also called peptic cells; Parietal cells, also called oxyntic cells; Gastroenteroendocrine cells, called enterochromaffin cells; and Stem cells.
• Gastric glands are present throughout the entire gastric mucosa except for regions occupied by cardiac and pyloric glands.
• In the muscularis, the enteric nervous system constitutes the myenteric plexus (also called Auerbach’s plexus).
• The submucosa is composed of a dense CT, variable amounts of adipose tissue and blood vessels.
• The serosa is continuous with the parietal peritoneum of the abdominal cavity via the greater omentum and with the visceral peritoneum of the liver at the lesser omentum.
• Bundles of unmyelinated nerve fibers and ganglion cells are present between inner and outer layers of the myenteric (Auerbach’s) plexus, which provides innervation of the muscle.
• Barrett’s esophagus is the replacement of the esophageal stratified squamous epithelium by columnar epithelium.
• The enteric nervous system, also known as the third division of the autonomic nervous system, is primarily responsible for innervating the smooth muscle layers of the alimentary canal and can function totally independently of the central nervous system.
• At the level of the distal pyloric antrum, the circular muscle layer thickens to form the annular pyloric sphincter.
• The submucosa contains a submucosal plexus or Meissner’s plexus, close to the inner muscle layer, and innervating the secretory glands, vessels and muscular mucosa.
• The muscularis externa consists of three poorly defined layers of smooth muscle oriented in circular, oblique and longitudinal directions.
• In the submucosa, the enteric nervous system constitutes the submucosal plexus (also called Meissner’s plexus).