1. The Digestive System 1131570114300 ELIMINATION Elimination is the body’s natural process for getting rid of waste products and is essential for general health and well-being. THE DIGESTIVE SYSTEM The task of the digestive system is the physical and chemical breakdown of food. Following ingestion the digestive organs process food and fluids into essential nutrients. These nutrients are absorbed from the intestines and circulated around the body. Any residue of food not digested is solidified and eliminated from the body in the form of faeces. The process of digestion begins when food enters the mouth and it is largely complete when it reaches the end of the small intestine. The digestive organs are as follows: Mouth Food enters the digestive system through the mouth and is cut, crushed and ground by the teeth. The tongue moves food around the mouth and the Salivary Glands add saliva that contains an enzyme, which begins the chemical breakdown process. This lasts approximately one minute. Pharynx When food is swallowed it travels down the pharynx or throat into the oesophagus. Oesophagus This is a thick walled muscular tube connecting the pharynx to the stomach. Swallowed food takes about 4.8 seconds to pass through it. Stomach This is a J-shaped muscular bag that churns, digests and stores food. This organ secretes Hydrochloric Acid and other enzymes that continue the chemical breakdown process, and kill bacteria. The food is processed and stored for approximately 2-4 hours. Duodenum The contents of the stomach empty into the duodenum where enzymes from the Gall bladder and the Pancreas are added to continue the chemical breakdown process. Liver The liver is like a processing factory and has many different functions. It removes toxins and waste from the blood and converts it into less harmful substances. It produces bile, which is a digestive enzyme that is stored in the Gall bladder. It produces proteins, and stores iron, vitamins and glycogen that can be used for energy. Pancreas The pancreas produces digestive enzymes and insulin which controls the body’s sugar levels. It also produces sodium bicarbonate which neutralises the hydrochloric acid in the stomach. Small Intestine This is the major site of digestion, where more digestive enzymes are added and the nutrients that are produced are absorbed into the body and used as energy, vitamins and minerals. Stomach contents take 3-5 hours to be processed. Large Intestine Undigested food enters the large intestine where water and salt is absorbed by the intestinal lining. The residue, together with waste pigments, dead cells, and bacteria, is pressed into faeces and stored for elimination from the body. Depending on the individual this can take anywhere between 10 hours to several days. Appendix This has no known function. Rectum Faeces pass into the rectum and are eliminated from the body via the anus. Anus The digestive tract ends at this body opening. Two sphincters, internal and external which act like valves that relax during defecation, control it.