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The digestion process.

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Introduction

Cheese salad sandwich? process through the body The sandwich is made up of different nutrients. Cheese contains fat and protein which are used to make things like enzymes and antibodies and for the growth and repair of tissues. The bread contains carbohydrates which is the main source of energy. The digestive system is responsible for breaking down food for it then to be absorbed into the blood stream for it to be carried to the cells of the body. The system has different parts to its structure that all take part in certain roles to complete the process of digestion. Digestion starts it process in the mouth. To start off the process we ingest the cheese sandwich into our mouth, we then use mechanical digestion which is when the sandwich is in our mouth and we use the back teeth to break down the larger pieces of food into smaller pieces. When we chew our food saliva is produced from our salivary glands. Saliva contains an enzyme amylase which breaks down the starch in bread, into maltose sugar. The mouth also makes lingual lipase begins to digest lipids, which are found in the cheese. Once the food is swallowed it is pushed through the oesophagus and the gastrointestinal tract by peristalsis. ...read more.

Middle

Bile is made in the liver but stored in the gall bladder. Bile doesn't contain enzymes but it does have salts that emulsify fats, increasing their surface area for lipase enzymes to work on. Pancreatic juice which is produced from the pancreas contains enzymes such as, trypsinogen which is activated by enterokinase in the small intestine to trypsin, that digests the partly digested proteins into smaller polypeptides. Amylase digests starch to maltose and lipase digests lipids to fatty acids and monoglycerides. The ileum has epithelial cells called enterocytes which contain enzymes embedded in their cell membranes. These enzymes protrude into the intestine so foods comes into contact. In the ileum, maltose digests to glucose by maltase and polypeptides are broken down to amino acids by peptidases. After 6-12 hours of the food being in the ileum the nutrients which are useful have been digested into smaller molecules. Carbohydrates have been broken down to simple sugars such as glucose, lipids have been broken down to fatty acids and monoglycerides and proteins have been broken down to amino acids. Food that is not absorbed into the blood at the ileum is passed into the large intestine. ...read more.

Conclusion

It is then carried to the lungs by the pulmonary artery, it then moves into the lungs to add oxygen. When oxygen enters the body it is done by breathing. Inspiration is when the muscles between the ribs contract and raise the ribcage up and out. He diaphragm muscles contract and flatten, the thoracic cavities volume increases which reduces the air pressure inside the thorax. Air moves down the pressure gradient from the atmosphere into the alveoli of the lungs this is where oxygen and carbon dioxide are exchanged. The lungs are adapted for gaseous exchange as they have a large surface area for diffusion of gases due to the fact they have millions of alveoli. In the alveoli the oxygen and nutrients are absorbed into the blood which is then moved into the aorta after passing through the heart to then be pumped out around the body. The transportation of blood throughout the body is down to blood vessels. The different types of blood vessels have different properties ad functions. Arteries are elastic and transport blood away from the heart. Whereas veins are again elastic but transport blood to the heart. Capillaries are small vessels that are found in tissues which transport blood from arteries to veins. ...read more.

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