The Digestive System is the system which makes nutrients and energy available to the body. There are many different organs needed to change the food we eat, into substances that can be used by the body.
The mouth is an opening that is used in breathing and digestion. It contains the tongue and teeth. The mouth in where the production of saliva occurs. Saliva is the first step in digestion, as it makes the food we pull in our mouth easier to chew and swallow. Salvia helps to break down certain carbohydrates. The teeth help by breaking down the food into smaller pieces. When you swallow the food is pushed down into the oesophagus.
The oesophagus is a muscular tube in the chest that connects the mouth and throat to the stomach. It lies immediately behind the trachea. The muscles in the wall of the oesophagus push food and liquids down into the stomach.
The stomach is a muscular bag-like structure located in the upper abdomen. The upper end is connected to the oesophagus and the lower is connected to the first section of the small intestine. Once food enters the stomach, it is stored and stomach acid is produced. The muscles in the stomach move the food and acid around, breaking the food down further. The acid kills bacteria that is contained in the food or salvia. Once the food has been processed into a thick liquid is leaves the stomach into the small intestine.
The small intestine is the longest portion of the digestive tract, about 6 meters long. It can be found in the middle of the abdomen. The small intestine is very flexible and mobile. The last few stages of digestion is performed in the small intestine. All the fats, protein and carbohydrates in the food is absorbed through the lining of the small intestine. These nutrients are taken to different parts of the body through the bloodstream.
The liver is the second largest organ in the body, weighing up to 3kg. It is located below the diaphragm and is protected by the lower ribs. The liver has two vital roles, making new chemicals and counteracting poisons and wastes. The nutrient filled blood which is from the small intestine, passes through the liver. The liver processes protein, carbohydrates and converts fats. The liver is also responsible for waste disposal. The liver produces bile, a substance that breaks down fats. Bile is transferred to the gallbladder, where it is stored until need for digestion. The glucose that is received from the small intestine is stored in the liver, so that when needed it can be released into the bloodstream as a source of energy. The liver also makes cholesterol and fats that are need in cells and hormones. Some of these fats are stored just like the glucose, for energy. The liver stores other substances like iron, vitamin B12 and copper.
The gallbladder is a small organ that is connected to the liver through small tubes. The gallbladder stores the bile, made in the liver. Bile becomes more concentrated in the gallbladder. The bile is released into the duodenum, the first part of the small intestine, where it breaks down fats.
The pancreas is a small flat organ, located behind the stomach. It has two main functions. In the pancreas, a substance of enzymes is made, which are needed to break down fats, carbohydrates and proteins. It also makes a substance that is used defuse stomach acid. Insulin is also made by the pancreas, which helps to maintain a balance in blood sugar levels.
The large intestine is about 1.5meters long and is located around the coil of the small intestine. The large intestine has several functions. It reabsorbs water and maintains a fluid balance, absorbs vitamins, processes undigested fibre, stores waste before it is eliminated and processes the waste in faeces.
The anus is the opening where faeces is passed out and eliminated from the body.