How Your Digestive System Works

Every day your body performs a digestive feat: seamlessly breaking down the foods you eat into small molecules of nutrients that are then absorbed into the blood and carried to cells throughout your body, providing you with the energy you need to live a full life. Despite this amazing feat, few people really understand how it works.

Your digestive system is made up of a digestive tract that includes the mouth, esophagus, stomach, small intestine, large intestine-also called the colon-rectum and anus, all connected by a long tube. These organs contain a lining of moist tissue called the mucosa. In the mouth, stomach and small intestine, the mucosa produces juices to help digest food. A layer of smooth muscle that lines the digestive tract also aids in breaking down food and moving it along the tract.

In addition to these organs, the liver and pancreas also produce digestive juices that travel to the intestine via small tubes called ducts. The gallbladder stores these digestive juices until the intestine needs them. The nervous and circulatory systems are also involved in helping your body digest food.

 How Your Food Is Digested

Digestion begins in your mouth. The food you swallow is then pushed into the esophagus and passes into the stomach. As the food dissolves into juices from the pancreas, liver and intestine, the contents continue to travel along the digestive tract. The digested nutrients are then absorbed through the intestinal walls and sent throughout your body. The waste products from this process, also known as feces, which include undigested parts of the food and cells that have been shed from the mucosa are pushed into the colon and then expelled by a bowel movement.

While the full digestion process can vary depending on each individual, usually it takes between 24 and 72 hours, although complete elimination from the body can take several days.

Common Digestive Complaints

With such a complex system at work, there are bound to be some hitches, including:

  • Belching. When air is swallowed when you eat or drink, the air collects in the stomach and gets pushed back out your mouth. Three to four burps after a meal is normal. More than that may signal an ulcer.
  • Gastroesophageal reflux disorder (GERD). This common disorder is usually the result of a lazy sphincter (valve) connecting the stomach and the esophagus, which allows acidic stomach contents to come back up into the esophagus, causing a burning sensation in the middle of the chest known as heartburn.
  • Flatulence. Flatulence occurs when a mixture of gases that are byproducts of the digestion process are passed through the rectum. Although embarrassing to talk about, it's normal to pass gas about 14 times a day.