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Introduction

A. Outline what is meant by a 'balanced diet' and explain why each component is required. 'A balanced diet is important to maintain health and a sensible body weight. No single food will provide all the essential nutrients that the body needs to be healthy and function efficiently. The nutritional value of a person's diet depends on the overall mixture, or balance, of food that is eaten over a period of time, as well as on the needs of the individual. A diet which includes a variety of different foods is most likely to provide all the essential nutrients.' (www.igd.com) The balanced diet must contain the following elements in the correct proportions: 1. Carbohydrates, 2. Protein, 3. Fats and oils, 4. Vitamins: A, B1, B2 etc up to B12, C, D, E 5. Mineral salts 6. Fibre (Roughage) 7. Water Each of the above are need to make the body work and there is negative affect to our bodies if we do get the correct amount or do with out them altogether. The following are the uses and what will happen if we do not the appropriate levels in our diet: 1. Carbohydrates: these provide a source of energy, if too much is consumed and you will gain excess weight and if too little is consumed you it will make you feel tired and lethargic. 2. Proteins: these provide a source of materials for growth and repair too much protein in the diet and you will gain weight and might make a lot of urine, too little protein in the diet and you will not grow properly and wounds will not heal. 3. Fats: these provide a source of energy and contain fat soluble vitamins. Fat transports the fat-soluble vitamins A, D, E and K around the body, it has a key role in membrane structure, it cushions, and so protects, the internal organs, it is stored in adipose tissue (a thick layer of tissue under the skin) as a long-term fuel reserve. ...read more.

Middle

Vitamins: vitamin E, Thiamin, B1, niacin, vitamin B5 and vitamin B6. Traces of vitamin C and vitamin A Digestion involves a number of different stages. The first phase is known as the cephalic (head) phase. It starts before food has even entered the mouth. The sight, smell, taste or even the thought of food will activate saliva in the mouth as well as digestive juices, which contain enzymes to break down food. During the entire journey of the food it will go through a stage called HYDRROLYSIS which is the breaking down of the bonds which keep the molecules in the in the different nutrients together, each nutrient has a different HYDROLITIC ENZYME which is explained in the following procedures. This is also illustrated in Table 4: A summary of the main human digestive enzymes. (Based on Boyle & Senior, 136) A. In the Mouth Once food is in the mouth, the taste buds begin determining the chemicals within the food via their nerve endings, in order to give the taste sensations of salt, sweet, sour or bitter. As your teeth and jaw muscles chew and grind the food, breaking it down (this is known as Mastication), it's mixed with saliva. This comprises many enzymes including the HYDROLITIC enzyme called Salivary Amylase, which begins to break down the long chains of starch found in the potatoes and the flour in the batter. Saliva also contains Mucin, a slimy glycoprotein lubricant (Boyle & Senior, 134) which moistens the food so it can pass easily through the digestive (gastrointestinal) tract. The tongue rolls it in to a ball or bolus which is just the right size to swallow. B. The Oesophagus After the food has been swallowed, it's carried down the oesophagus (a muscular tube) towards the stomach. The oesophagus can contract and relax in order to propel the food onwards this is called Peristalsis and each mouthful of food takes about six seconds to reach the stomach once swallowed. ...read more.

Conclusion

OXIDISED ENERGY 3. Fatty Acids and Glycerol These travel around in the blood and they can be used by the cells for structural purposes such as producing call membranes or they can be oxidised to produce energy. Any excess fat can be stored under the skin as SUB-CUTANIOUS FAT or ADIPOSE TISSUE. This acts as a food store as well as an insulator helping to maintain body temperature. (Class notes) E. The large intestine The unabsorbed residue of this process finally reaches the end of the small intestine and enters the large intestine. It is named for its wide diameter. The large intestine has six parts: the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and r****m. This is one of the most metabolically active organs in the body. It measures about 1.5 metres and contains over 400 different species of bacteria that break down and utilise the undigested residues of our food, in the first part of the large intestine, the colon, the only things left to be absorbed is mostly water, dietary fibres (roughage) and vitamins and minerals of the meal of fish and chips. As the watery contents move along the large intestine still using the process of peristalsis, water is absorbed and the final product - faeces - is formed, which is stored in the r****m before excretion (defecation) from the body through the sphincter at the a**s. Organ What Happens Here Mouth 1. Mechanical digestion of all food (teeth chewing & grinding) 2. Chemical digestion of carbohydrates begins. Oesophagus Food passes from mouth through the oesophagus to the stomach. Stomach 1. Mechanical digestion of food (churning of stomach walls). 2. Chemical digestion of proteins begins. Small Intestine 1. Chemical digestion of carbohydrates, proteins, & lipids continues & is completed. 2. The small, soluble nutrients (sugars, amino acids, fatty acids) are absorbed. Large Intestine Water is absorbed from unusable, indigestible wastes (faeces) Table 5: ORGANS OF the ALIMENTARY CANAL Note: The structures are listed in the order in which food passes through them. ?? ?? ?? ?? Access To H.E. Biology II ASSIGNMENT ON NUTRITION 1 Ashley Spirit ...read more.

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