Digestion is the process in which food is broken down into nutrients used by the body. Food passes from the mouth through the esophagus to the stomach. The stomach churns the food and breaks it down further with its contents of hydrochloric acid and an enzyme called pepsin.
The process of breaking food down in the stomach takes a few hours. From there, it goes to the duodenum where it is broken down further by digestive bile produced by the liver and stored in the gallbladder along with enzymes from the pancreas. Enzymes are chemicals that speed up the digestion of specific types of food. For example, the enzyme trypsin breaks down the protein in steak, lipase helps to break down fat, and lactase breaks down the sugar in milk.
Once everything is broken down, the small intestine absorbs the nutrients the body needs. From there the nutrients go into the bloodstream and to the liver, where poisons are removed. Undigested food and water continue through the small intestine and go into the large intestine, where water is reabsorbed. Finally, feces are eliminated through the rectum and anus.