About Digestive System
The digestive system turns food into molecules small enough to absorb and use. Digestion begins in the mouth and continues through the stomach and intestines, with important help from the liver, gallbladder, pancreas, nerves, muscles, hormones, and gut microbes.
Mouth
Chewing and saliva begin mechanical and chemical digestion.
Learn MoreEsophagus
The esophagus is a muscular tube connecting the throat to the stomach.
Learn MoreStomach
The stomach stores food, mixes it, and begins major protein digestion.
Learn MoreSmall Intestine
Most nutrient absorption occurs in the small intestine.
Learn MoreLiver and Gallbladder
The liver processes absorbed nutrients and produces bile.
Learn MorePancreas
The pancreas sends digestive enzymes and bicarbonate into the small intestine.
Learn MoreLarge Intestine
The colon absorbs water and houses dense microbial communities.
Learn MoreGut Microbiome
Trillions of microorganisms live in the digestive tract.
Learn MoreMouth
Teeth break food into smaller pieces, while the tongue moves it and mixes it with saliva. Salivary enzymes begin digesting some carbohydrates, and swallowing moves food into the esophagus.
Esophagus
Waves of muscle contraction called peristalsis push swallowed material downward. These coordinated contractions mean food can move toward the stomach even when body position changes.
Stomach
Strong muscular walls churn food with acid and digestive enzymes. A protective mucus barrier helps shield the stomach lining from its own acidic contents.
Small Intestine
Its inner surface is covered with folds, villi, and microscopic microvilli that greatly increase surface area. Digested sugars, amino acids, fats, vitamins, minerals, and water move into blood or lymph.
Liver and Gallbladder
Bile helps the digestive system handle fats. The gallbladder stores and concentrates bile before releasing it into the small intestine. The liver also performs hundreds of chemical, storage, detoxification, and metabolic tasks.
Pancreas
These enzymes help break down proteins, carbohydrates, and fats. Bicarbonate helps neutralize acidic material arriving from the stomach. The pancreas also makes hormones, including insulin and glucagon.
Large Intestine
Material that remains after small-intestine digestion enters the large intestine. Water and electrolytes are absorbed, microbes ferment some remaining compounds, and the final waste is formed.
Gut Microbiome
Gut bacteria help process certain fibers and produce many chemical compounds. The microbiome varies from person to person and changes with diet, age, medicines, illness, and environment.