Digestion is a process involving enzymes, or digestive proteins, that chemically break down food into smaller nutrients. The digestive system includes the mouth, esophagus, stomach and intestines. Digestive enzymes found in saliva start digesting food the moment it enters your mouth, but the majority of digestion occurs in the stomach and intestines. According to the National Institute of Diabetes and Digestive and Kidney Diseases food must be broken down from protein, carbohydrate and fat sources before it can be absorbed into the blood stream.
Mouth
Digestive proteins start breaking down carbohydrates in the mouth. Amylase is released from the salivary glands the moment food enters the mouth. Chewing mixes amylase into food pieces allowing the digestive process to begin. Salivary amylase breaks down carbohydrates into maltose, which is a more soluble sugar.
Stomach
Food transported to the stomach through the esophagus is now called chyme. This food is still not digestible. The stomach releases acid and pepsin to further break down carbohydrates, fats and proteins. The stomach is assisted by the release of digestive enzymes from the pancreas. Trypsin and pepsin work in the stomach to break down proteins into amino acids. Pepsin also signals the liver to produce bile. The stomach relies on the pancreas to release digestive proteins such as lipase and amylase to further reduce fats and carbohydrates.
Intestines
Fat is primarily digested and absorbed in the intestine. Lipase is the enzyme responsible for breaking down fats into fatty acids. Trypsin and chymotrypsin are produced by the pancreas but released through the intestinal muscosa to break down different proteins. The intestines further break down starches into their smallest compounds. Sucrase, maltase, isomaltase and lactase are all enzymes that further break down carbohydrates.
Pancreas
The gastric glands of the pancreas release the majority of the enzymes that assist the stomach and intestine in digestion. Pancreatic amylase helps to turn carbohydrates into glucose . Proteins must be broken down into amino acids. Trypsin, chymotrypsin, and carboxypeptidase all help create amino acids. The pancreas also releases lipase, which breaks down fats into glycerol and fatty acids.
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