Anatomy of the Digestive System (cont.)
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Once food is swallowed, it enters the esophagus, a muscular tube that is about 10 inches long. The esophagus is located between the throat and the stomach. Muscular wavelike contractions known as peristalsis push the food down through the esophagus to the stomach. A muscular ring (cardiac sphincter) at the end of the esophagus allows food to enter the stomach, and, then, it squeezes shut to prevent food and fluid from going back up the esophagus.
The stomach is a J-shaped organ that lies between the esophagus and the small intestine in the upper abdomen. The stomach has 3 main functions: to store the swallowed food and liquid; to mix up the food, liquid, and digestive juices produced by the sto mach; and to slowly empty its contents into the small intestine.
Only a few substances, such as water and alcohol, can be absorbed directly from the stomach. Any other food substances must undergo the digestive processes of the stomach. The stomach's strong muscular walls mix and churn the food with acids and enzymes (gastric juice), breaking it into smaller pieces. About three quarts of the gastric juice is produced by glands in the stomach every day.
The food is processed into a semiliquid form called chyme. After eating a meal, the chyme is slowly released a little at a time through the pyloric sphincter, a thickened muscular ring between the stomach and the first part of the small intestine called the duodenum. Most food leaves the stomach by four hours after eating.
Medically Reviewed by a Doctor on 4/22/2016
Sandeep Mukherjee, MD, MB, BCh
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