ASGE Recognized Industry Associate (ARIA) Training Program OPEN | April 2022-Esophagus and Stomach In Health

Pdf Summary
The esophagus is responsible for moving food from the mouth to the stomach. It also begins digesting proteins and fats in the food before it reaches the stomach. The lining of the esophagus is typically the same columnar mucosa found in the rest of the gastrointestinal (GI) tract. <br /><br />The stomach is the main location for food digestion and grinding it down into small pieces to increase surface area for digestion and absorption. It is not the main location for nutrient absorption. <br /><br />The GI tract consists of various digestive organs, including the pancreas, esophagus, stomach, gallbladder, liver, small intestine, and large intestine. <br /><br />Digestion involves the breakdown of food into smaller components to facilitate the absorption of nutrients and minerals. It is necessary for growth, metabolism, body maintenance, and reproduction. Digestion can occur through both chemical and mechanical means, involving substances like saliva, gastric acid, pancreatic enzymes, and bile. The mechanisms of digestion include mastication, peristalsis (muscular contractions that propel food forward), and segmentation (mixing food with simultaneous contraction). <br /><br />The process of digestion involves three main steps: motility, secretion, and absorption. Motility refers to the muscular movements of the GI tract, including peristalsis and segmentation. Secretion involves the release of acid and enzymes to mix with food. Absorption occurs when nutrients and water are absorbed by the GI tract into the bloodstream. <br /><br />The journey of digestion starts in the mouth, where food is mechanically broken down through chewing and saliva is produced to assist in swallowing. The esophagus is a hollow muscular tube that transports saliva and food from the mouth to the stomach. Its walls consist of layers such as the mucosa, submucosa, circular muscle, longitudinal muscle, and muscularis mucosa. The upper part of the esophagus contains skeletal muscle, while the lower part contains smooth muscle. The gastroesophageal junction is where the lower esophageal sphincter is located, preventing backflow of stomach acid and food into the esophagus. <br /><br />The stomach is a J-shaped reservoir of the digestive tract where food mixes with acid and enzymes for further breakdown. Partially digested food is released into the small intestine. The stomach is made up of different parts, including the fundus, body, greater curvature, lesser curvature, pylorus, antrum, lower esophageal sphincter, and cardia. Its mucosa has rugae, and its layers consist of surface epithelium, lamina propria, oblique layer, circular layer, longitudinal layer, muscularis mucosa, submucosa, muscularis propria, and serosa. The stomach also secretes gastric acid through various cells, including parietal cells, chief cells, and enteroendocrine cells.
Asset Subtitle
Brooke R. Glessing, MD
Keywords
esophagus
food movement
digestion
gastrointestinal tract
stomach
nutrient absorption
small intestine
gastric acid
pancreatic enzymes
bile