The path that food follows through the digestive system is very interesting. First you put the food to your mouth, take a bite, and chew. The salivary glands begin the digestive process at the sight and smell of food. After food enters the mouth and is moistened by saliva, it transforms into a bolus. Once the bolus leaves the mouth, it moves into the pharynx, where it can be swallowed. The bolus then moves from the pharynx to the stomach.
Once the bolus reaches the stomach, it is mixed with acid secretion to transform the bolus into chyme (the semifluid mass into which food is converted by gastric secretion and which passes from the stomach into the small intestine). Food is partially digested in the stomach and chyme usually empties from the stomach in two to six hours. This time frame can be determined by the size and type of meal ingested. Although, the liver, gallbladder, and pancreas are located in close proximity of the stomach, they contribute to the digestive process once the chyme reaches the small intestine.
The small intestine is a tube shaped organ of the digestive tract where digestion of ingested food is completed and the majority of nutrient absorption occurs. The small intestine is divided into three parts, known as the duodenum, the jejunum, and the ileum. The large intestine includes both the colon and the rectum. Additional absorption of water and some vitamins and minerals occurs in the colon. Materials not absorbed in the colon are exerted from the body as waste products in the feces. The end of the colon is attached to the anus, which is the external opening of the digestive tract where the feces are eliminated from the body.