The digestion process begins when food is either smelled or seen. The mouth instantly produces saliva from the parotid, sub maxillary, and the sublingual glands moistening the mouth in preparation for food. Food enters the mouth and chewed by the incisors, canines, premolars, and the molars chewing and grinding it into a bolus and mixing it with more saliva to help lubricate and begin the process of absorption of the vital nutrients contained in the food.
After the food is chewed enough it is then forced down the esophagus in a process peristalsis, a series of rhythmic muscular contractions that moves the food into the stomach. The stomach and the esophagus are connected by the cardiac sphincter. The cardiac sphincter is controlled by muscles that open and close allowing food to enter and stay in the stomach. The stomach stores the food until enough of the digestive enzymes called pepsinogen and hydrochloric acid.
When enough enzymes are produced the stomach begins to churn and mix the acids and food together to produce a soupy liquid chyme. During this process large proteins are broken down into smaller ones called peptides and digested. Finally mucus is produced to protect the stomach lining from all of the acids that are produced during this process, without this mucus the stomach lining would have continuous ulcers in it. The chime is then passed from the stomach through another sphincter into the small intestine.
The small intestine is roughly 23 feet long and is made up of three sections, the duodenum, jejunum, and the ileum. The most of the digestion process happens in the duodenum, enzymes digest nutrients into simpler forms that are absorbed. The pancreas releases enzymes that supplement intestinal enzymes to aid in even more digestion of nutrients and proteins. The gall bladder produces bile to help in fat digestion, the bile enters the small intestine at this point in the digestion process. Enzymes that aid in the digestion of carbohydrates...