ASGE Recognized Industry Associate (ARIA) Training Program for Regeneron | June 2022-GI_Tract_in_Health-Esophagus_Stomach

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The gastrointestinal tract is a continuous tube that runs from the mouth to the anus and is responsible for digestion, absorption, and elimination. The esophagus and stomach are two key organs in the digestive process. Digestion begins in the mouth with the mechanical breakdown of food through chewing and saliva production. This saliva, which contains amylase, aids in carbohydrate digestion. The esophagus is a muscular tube that transports food and saliva from the mouth to the stomach. It has four distinct layers and is collapsed at rest. Swallowing is the process of moving food from the mouth to the esophagus, and there are three phases of swallowing: oral, pharyngeal, and esophageal. Motility, secretion, and absorption are the key components of digestion. Motility refers to the muscular movements of the GI tract, including peristalsis and segmentation, which propel food forward and mix it with simultaneous contractions. The esophagus is made up of two types of muscle: skeletal muscle in the upper third and smooth muscle in the lower two-thirds. The lower esophageal sphincter, located at the gastroesophageal junction, relaxes with swallows and contracts to prevent stomach acid and food from flowing back into the esophagus. The stomach functions as a reservoir for food and mixes it with acid and enzymes for digestion. It has different parts, including the fundus, body, greater curvature, lesser curvature, pylorus, and cardia. The stomach mucosa has rugae and gastric folds, while the muscularis has three layers: longitudinal, circular, and oblique. The stomach produces gastric acid through the action of gastrin, parietal cells, and acid-producing enzymes.

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Jennifer R. Lightdale, MD, MPH, FASGE

Keywords

gastrointestinal tract

digestion

esophagus

stomach

swallowing

motility

peristalsis

lower esophageal sphincter

gastric acid

enzymes