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1 of 41 © Boardworks Ltd 2008 2 of 41 © Boardworks Ltd 2008 A balanced diet Diet is the usual food and drink that each person consumes and is a very important part of health. A balanced diet means eating the right types of food in the right amounts so that the body gets the nutrients it needs. What are the seven nutrients needed in a balanced diet? carbohydrates minerals proteins water fats fibre vitamins Which foods contain these nutrients, and why are they important? 3 of 41 © Boardworks Ltd 2008 Getting the amounts right 4 of 41 © Boardworks Ltd 2008 Types of nutrients 5 of 41 © Boardworks Ltd 2008 Nutrients in food 6 of 41 © Boardworks Ltd 2008 Eating too little Many people do not have access to enough food. A lack of nutrients can result in malnutrition. Malnutrition is a major health problem. It increases the risk of disease and early death. There are several reasons why people might not have enough food, including: natural disasters poverty war A lack of just one specific nutrient can cause a deficiency disease, like anaemia or scurvy. 7 of 41 © Boardworks Ltd 2008 Eating too much Eating too much means that the body consumes more energy than it uses and so the excess starts to build up. People who are very overweight for their height are said to be obese. Currently, 17% of 15year-olds in the UK are classified as being obese. Obesity is a serious health problem as it affects the heart, blood pressure and can lead to joint problems. 8 of 41 © Boardworks Ltd 2008 Deficiency diseases 9 of 41 © Boardworks Ltd 2008 Digestion 10 of 41 © Boardworks Ltd 2008 The stomach As food moves through the digestive system it is broken down. Useful food molecules and water are absorbed into the body. After food is swallowed, it enters the stomach. food enters from the gullet Two things happen to food in the stomach: the chemical breakdown of food begins microbes are destroyed. muscle tissue food leaves the stomach From the stomach, food enters the small intestine where digestion is completed and the small digested food molecules are absorbed into the bloodstream. 11 of 41 © Boardworks Ltd 2008 The intestines After the small intestine, the remains of the food travels to the large intestine. All that is left of the food is water and waste material. The water is valuable, so it is absorbed from the large intestine into the bloodstream. The waste material cannot be digested or used by the body. small intestine The undigested waste travels to the rectum where it is stored until leaving the body through the anus. 12 of 41 large intestine © Boardworks Ltd 2008 Organs of the digestive system 13 of 41 © Boardworks Ltd 2008 What is digestion? The body carries out digestion of food to convert large insoluble food molecules into smaller soluble ones. carbohydrate molecule protein molecule fat molecule Large food molecules cannot pass through the walls of the small intestine. Small food molecules can do this when dissolved in the bloodstream. Why is this important? 14 of 41 © Boardworks Ltd 2008 What are carbohydrates? Starchy foods contain carbohydrates, which are made of long chains of identical, small sugar molecules. one sugar molecule carbohydrate molecule The body breaks down long chains of carbohydrates into the smaller sugar molecules. These small sugar molecules are used by the body to release energy and make the body work. 15 of 41 © Boardworks Ltd 2008 What are proteins? Proteins, like carbohydrates, are made of long chains of small molecules. In proteins, these small molecules are not identical. one amino acid protein molecule Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid. Proteins are used by the body for growth and repair. 16 of 41 © Boardworks Ltd 2008 What are fats? Fats are made up of fat molecules, which contain fatty acids and glycerol. fatty acids glycerol fat molecule Fat molecules have to be broken down by the body so that they can be used for energy storage. Fats are also used by the body to keep heat in and to make cell membranes. 17 of 41 © Boardworks Ltd 2008 Digestive enzymes How do digestive enzymes help the process of digestion? 18 of 41 © Boardworks Ltd 2008 Different types of digestive enzymes Digestive enzymes are the chemicals that break large insoluble food molecules into smaller soluble molecules. Digestive enzymes are classified by the type of food that they affect; there are three main types: carbohydrase – breaks carbohydrate into smaller sugars protease – breaks protein into amino acids lipase – breaks fat into fatty acids and glycerol. 19 of 41 © Boardworks Ltd 2008 How do enzymes work? 20 of 41 © Boardworks Ltd 2008 Carbohydrate digestion Carbohydrates are chains of identical sugar molecules. The digestive enzyme called carbohydrase breaks the chemical bonds between the individual sugar molecules in each carbohydrate chain. carbohydrase long carbohydrate molecule 21 of 41 sugar molecules © Boardworks Ltd 2008 Protein digestion Proteins are made up of amino acids. There are over 20 different types of amino acids. Proteins are digested by digestive enzymes called proteases. These enzymes work in an acidic environment to break proteins into smaller amino acids. protease long protein molecule 22 of 41 amino acid molecules © Boardworks Ltd 2008 Fat digestion Fats are digested in two stages. Firstly, bile (released by the gall bladder) allows the fat to ‘mix’ with water by breaking the fat into smaller droplets. This is called emulsification. bile Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol and fatty acid molecules. lipase fat molecule 23 of 41 + glycerol fatty acids © Boardworks Ltd 2008 Which enzyme? 24 of 41 © Boardworks Ltd 2008 The process of digestion 25 of 41 © Boardworks Ltd 2008 Label the digestive system 26 of 41 © Boardworks Ltd 2008 Summary 27 of 41 © Boardworks Ltd 2008 Fitness 28 of 41 © Boardworks Ltd 2008 What is health? Health is a state of complete mental, physical and social well-being, and the absence of disease or infirmity. So a healthy person is: physically well mentally well socially happy free from disease. What is the difference between health and fitness? 29 of 41 © Boardworks Ltd 2008 What is fitness? Fitness is the ability to meet the demands of the environment. So, fitness is not necessarily about how far you can run or how good you are at sport. Being fit means being physically able to cope with the demands of everyday life. These demands will vary from person to person, depending on things like lifestyle, occupation and age. 30 of 41 © Boardworks Ltd 2008 What is fitness? Fitness is made up of four factors – “the four S’s”: fitness suppleness stamina strength speed How do these fitness factors help us in everyday life? 31 of 41 © Boardworks Ltd 2008 Fitness factors 32 of 41 © Boardworks Ltd 2008 Why exercise? Regular exercise can help to keep you healthy, by: strengthening the heart, reducing the risk of heart disease strengthening bones, reducing the chances of osteoporosis reducing stress, by releasing mood-enhancing chemicals in the brain. Exercise also helps to maintain and improve fitness. 33 of 41 © Boardworks Ltd 2008 Why exercise? 34 of 41 © Boardworks Ltd 2008 Which factor? 35 of 41 © Boardworks Ltd 2008 Staying fit and healthy You should aim to do a minimum of 30 minutes of moderately intense exercise at five times a week (or more). However, exercise can be hazardous if done inappropriately. Injuries are common from lifting weights that are too heavy and running on hard surfaces without proper footwear. How can poor exercise cause injury to muscles and joints? 36 of 41 © Boardworks Ltd 2008 Different types of joints 37 of 41 © Boardworks Ltd 2008 Summary activities 38 of 41 © Boardworks Ltd 2008 Glossary 39 of 41 © Boardworks Ltd 2008 Anagrams 40 of 41 © Boardworks Ltd 2008 Multiple-choice quiz 41 of 41 © Boardworks Ltd 2008