The digestive system is uniquely constructed to turn food into molecules absorbed and utilised by the body's cells. From the mouth to the anus, the digestive system is a long, continuous passageway of various organs, which all play a vital role in digestion. Food is broken down, bit by bit, until the molecules are small enough to be absorbed in the small intestine and the waste products are eliminated out of the anus. The digestive system includes the digestive tract and its accessory organs. The digestive tract, also called the alimentary canal or gastrointestinal (GI) tract, includes the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus. The tongue and teeth supporting the digestive tract are accessory structures located in the mouth for mastication. The major accessory organs essential for digestion are the salivary glands, liver, gallbladder, and pancreas, which secrete fluids into the digestive tract.