The Digestive System

The Digestive System[pic 1]

Unit 11 (P2)

In this assignment I am going to talk about the digestion system and how it all works in order to convert food into basic nutrients to help the body function normally as well as providing energy for the body. Digestion is when large particles are broken down into smaller particles that then can be used by the body.[pic 2][pic 3][pic 4][pic 5][pic 6][pic 7][pic 8][pic 9][pic 10][pic 11][pic 12][pic 13][pic 14]

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Structure of the digestive System

Food enters the mouth or can also be referred to as the Buccal cavity, and is then chews up by the teeth, it is then mixed with saliva that comes from the tongue.  Smell and taste from the food will then trigger off the salivary glands. This then travels down to the oesophagus travels between the neck and the thorax. The food that is swallowed down to the oesophagus is moved from rhythmic muscular contractions. This is also known as peristalsis. Peristalsis occurs when contractions happen in longitudinal and circular bands of muscle. Antiperistalsis is the reverse of swallowing and is usually known as vomiting. The action of vomiting is usually aided by the contraction of the abdominal muscles. This then leads down to the stomach, which is located to left of the liver and underneath the diaphragm. It is the widest part of the alimentary canal and acts a store for food that has been chewed up and transported by the oesophagus. The food that is stored in the stomach can stay there from 2 hours all the way to 6 depending on how quickly it gets digested by the acids in the stomach, when the food is getting digested it is also mixed with hormones, enzymes and hydrochloric acid, as well as other chemicals that help with digestion. The average stomach size can store up to a volume of 1 litre, as well as this the stomach is also able to expand to store a little more food. When the stomach is getting full and starting to expand, it sends stimuli to the brain to tell us that we are getting full and to stop eating. The wall of the stomach is lined with mucus which protects it from the acids inside the stomach, if the mucus isn’t there then it could lead to stomach ulcers. Food when digested moves on through the pylorus sphincter to the small intestines. The duodenum is the first part of the small intestines and is also the smallest part; the duodenum receives chyme (partially digested food). It plays a vital part of the chemical digestion of the chyme; this then leads to the preparation of absorption from the small intestine. The liver is important in our body as it helps filter blood as well as acting like a large reservoir. The important functions of the liver is it metabolises things that are digested by the body such as protein, fats and carbohydrates.it helps store vitamins that the body need to function.  It also converts glycogen into glucose, which is an energy source that is required by the body, the Gall bladder also supports break down of food as it helps get fats into our bodies, this helps by emulsifying the fats by using concentrated bile. The small intestines if it is stretched are around 7 meters long in an average adult. It is made up of the duodenum, ileum and jejunum. The bile and pancreatic ducts open into the duodenum together. Since the small intestines is so long, absorption of minerals occurs here and the last remaining nutrients has been taken to be used by the body, this is because of a huge blood supply around this area. If any digestion does happen in the small intestine it relies on its own secretions, as well as the ones that have been passed down from the liver, gall bladder and pancreas.  The small intestines then leads into the large intestines length is 1.5 meters, which is shorter than the small intestines. The large intestine is made up of the appendix, caecum, colon and the rectum. The large intestines are one of the last stages of the absorption and are on the way to excretion. Food cannot return from the large intestines due to the contraction of the ileo-colic valve, which exerts pressure. The water that is left will be absorbed by the surrounding intestines walls. The faeces are then moved through the colon and then into the anal canal where the waste is removed from the body. The kidneys make sure that the composition of our blood is constant; making sure that the excess water and waste products are excreted through urine does this. Our body filters around 150 litres of blood and also produces around 1.5 litres of urine. The digestive juices and enzymes that are in the body are there to help break down the food, the digestive juices are found in the stomach lining and the enzymes are also found in the juices from the stomach as well as pancreas, the enzymes help speed up the metabolism as well.