Human Digestion

Food must enter the digestive tract through the mouth; where the salivary glands process the sight and smell of food. The tongue permits for taste and the manipulation of food while chewing while preparing the food to be swallowed. The teeth break the food down into smaller and softer pieces when mixed with saliva, called a bolus. The bolus goes from the mouth to the pharynx, also-called the throat, down the esophagus.

The esophagus is a tube connecting the pharynx to the stomach. When food enters the stomach, the acids in the stomach begin to liquefy the softened food. The liquefied version of food is known as chyme. Food is partially digested into the stomach and usually empties within two to six hours, depending on the size of the meal.

The small intestines are connected to the stomach where a majority of nutrient absorption occurs. Assisting the small intestines in this process and the remaining digestion are the liver, gall bladder, and pancreas. While the liver produces bile that helps to digest fat, the gall bladder stores this bile. The pancreas secretes enzymes and bicarbonate into the small intestines to help aid in the digestion.

The majority of the digestion process occurs in the small intestines. The small intestine is divided into three parts, called duodenum, jejunum, and ileum. Foods not absorbed in the smaller intestines, pass to the large intestines through the sphincter that prevents food from re-entering the small intestines. The large intestines include the colon and rectum, where additional water, some vitamins, and minerals are absorbed. Material remaining is excreted from the body at the end of the colon through the anus as feces.