Student Projects/Human Digestive System
Human digestive system
The human digestive system is the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract, or the series of structures and organs through which food and liquids pass during their processing into forms absorbable into the bloodstream. The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process.
ALIMENTARY CANAL : The alimentary canal is a major part of the digestive system. It is a continuous muscular tube which runs through the body and it is around 8 to 10 meters long. It is open at 2 ends, with the mouth at the anterior end and anus at the posterior end.
MOUTH : The mouth consists of the oral cavity, through which food is ingested. It is bounded by lips and cheeks. It contains gums, teeth, a tongue and muscles. The tongue tastes food and moves it into the pharynx. Teeth help in biting, cutting and chewing food. Teeth masticate the food. This makes it easier to swallow food and increases its surface area for various digestive secretions to act on. The four types of teeth are incisors, canines, premolars and molars. Our teeth are covered with a hard protective covering of enamel.
PHARYNX : The oral cavity opens into the pharynx. The swallowing mechanism guides the masticated food through the pharynx, into a tube called oesophagus.
OESOPHAGUS : It is a muscular, tubular part of the alimentary canal. The muscular walls of the oesophagus move in a rhythmic wavelike manner, which carries the food down to the stomach. This muscular movement is called peristalsis. Here also salivary amylase acts on starch and glycogen in the chewed food.
STOMACH : It is located below the diaphragm (the muscular partition between the chest cavity and abdominal cavity). It is a saclike muscular structure. It serves as a storehouse of food where partial digestion takes place.
SMALL INTESTINE : The small intestine is about 6 meters in length and 2.5 of the small intestine: duodenum, jejunum and ileum. most of the absorption of nutrients and minerals from food takes place in small intestine.
LARGE INTESTINE : The large intestine is wider and shorter than the small intestine approximately 1.5 metres, or 5 feet, in length.Function of large intestine is to observe some undigested food and salt from the food material.
ABSORPTION OF DIGESTED FOOD : Absorption of completely digested food takes place in the ileum. The wall of the ileum has finger-like projections called villi that increase the surface area for absorption of digested food. The villi are richly supplied with blood vessels to carry the absorbed food. The absorbed food is then brought into the blood capillaries. From the blood capillaries, absorbed materials are transported by veins to the liver and then to the heart for distribution to different parts of the body.