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1 of 36© Boardworks Ltd 2006. 2 of 36© Boardworks Ltd 2006.

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Presentation on theme: "1 of 36© Boardworks Ltd 2006. 2 of 36© Boardworks Ltd 2006."— Presentation transcript:

1 1 of 36© Boardworks Ltd 2006

2 2 of 36© Boardworks Ltd 2006

3 3 of 36 A history of fad diets Which diets are designed for weight loss? Which diets have a scientific basis?

4 © Boardworks Ltd of 36 You are what you eat! When food is digested its components enter the blood. Molecules used for growth and repair become part of the body. Those used as energy sources are lost as CO 2 and H 2 O. protein glucosecarbohydrate fatfatty acids + glycerol amino acids

5 © Boardworks Ltd of 36 What are cells made from? Different nutrients are incorporated into each part of a cell: nucleus: protein membrane: fats and carbohydrate cytoplasm: protein and water

6 © Boardworks Ltd of 36 You are what you eat! What could this food label represent? A human!

7 © Boardworks Ltd of 36 Different nutrients

8 © Boardworks Ltd of 36 The amount of each type of nutrient a person needs varies between individuals. What factors might affect how much a person needs? Dietary guidelines carbohydrate (50%) vitamins and minerals (1%) protein (14%) fat (35%)

9 © Boardworks Ltd of 36 A protein deficiency illness called Kwashiorkor can cause a swollen belly and weak immune system, and is common in developing countries. Proteins in meat and fish are called first-class proteins because they contain all the essential amino acids that humans need in their diet. Lack of protein What is the RDA of protein for a 60 kg student? Recommended daily allowance (RDA) of protein (g) = 0.75 x body mass (kg) RDA = 0.75 x 60 kg = 45 grams

10 © Boardworks Ltd of 36 Why do some people need more food? Metabolism is the series of chemical reactions or life processes in the body. Different amounts of energy are used in different life processes. exercise and warmth (20%) digestion (10%) growth and repair (70%) Metabolic rate is the rate at which cells uses energy, and this varies between individuals. Why does metabolic rate increase during exercise and cold weather?

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12 12 of 36 Chemical and physical digestion

13 © Boardworks Ltd of 36 Enzymes digest food in the mouth, stomach and small intestine. Enzymes at work Enzymes break down large food molecules into smaller ones that can be absorbed by the blood. This is called chemical digestion. Different types of food are broken down by different enzymes.

14 © Boardworks Ltd of 36 Enzymes of digestion

15 © Boardworks Ltd of 36 Helping enzymes Enzymes are not the only substances involved in chemical digestion. Bile is a substance produced by the liver and stored in the gall bladder. It helps the digestion of fats by turning them into small droplets. This is called emulsification. How does this help lipase enzymes? Hydrochloric acid in the stomach provides the right conditions for protease enzymes to break down protein. The smaller droplets have a larger surface area, which speeds up the rate at which lipase digests the fat.

16 © Boardworks Ltd of 36 Which enzyme?

17 17 of 36© Boardworks Ltd 2006

18 18 of 36 What is BMI? Body Mass Index (BMI) measures the relative amounts of fat and muscle in the body. BMI = body mass (kg) (height) 2 (m) underweight normal overweight obese < >30 BMIConclusion Obese people have an increased risk of arthritis, diabetes and heart disease. People who are underweight tend to have poor immune systems and often get ill. What are their health risks? Zak: BMI = m and 66 kg Gloria: BMI = m and 66 kg

19 © Boardworks Ltd of 36 Are you right for your height? This means it is helpful to use extra measures to help judge how healthy a person is, such as waist circumference. This is because muscle is denser than fat. Calculating a persons BMI can be useful, but the formula can overestimate the proportion of body fat in people who are muscular. In 2002, 22% of boys and 28% of girls aged 2-15 in the UK were overweight or obese. Statistics show that obesity levels, among both young people and adults, are rising.

20 © Boardworks Ltd of 36 Blood pressure is a measure of the pressure exerted by the blood against artery walls. Blood pressure varies with: What is blood pressure? Blood pressure is measured as two numbers, e.g. 120/80. What do these numbers show? The numbers show pressure readings in mm of mercury. heartbeat strength blood volume fitness health age.

21 © Boardworks Ltd of 36 The big number (120) is the systolic pressure. This is the blood pressure during a heartbeat. Blood pressure one-twenty over eighty. Systolic and diastolic The small number (8) is the diastolic pressure. This is the blood pressure in-between heartbeats.

22 © Boardworks Ltd of 36 How does blood pressure affect health? Low blood pressure can cause dizziness, fainting and poor circulation. High blood pressure can make blood vessels more likely to burst, and can cause strokes and kidney damage AgeSystolicDiastolic The older you get, the higher your blood pressure naturally becomes. Kevin is 38 years old and his blood pressure is 180/90. What advice would you give him?

23 © Boardworks Ltd of 36 Lifestyle assessment Kevins GP quizzed him about his lifestyle, tested his blood and referred him to a health centre. What else could Kevin do to improve his health? Excess salt is known to increase blood pressure in about 30% of the population.

24 © Boardworks Ltd of 36 Health and physical fitness are different. Kevins GP wants his cardiovascular fitness to improve so that he puts less strain on his body. His personal trainer wants other sorts of fitness to improve. Health and fitness What types of exercise should Kevin do? A healthy person is free from disease or abnormality. A fit person has good cardiorespiratory, aerobic and muscular endurance.

25 © Boardworks Ltd of 36 Fast food and takeaways such as curries, burgers and pizzas are high in unhealthy nutrients such as saturated animal fats, sugar and salt. Fast food usually contains very little fibre, vitamins, minerals or unsaturated vegetable oils, which are important for a healthy diet. What is wrong with fast food?

26 © Boardworks Ltd of 36 Unhealthy diets?

27 © Boardworks Ltd of 36 Cholesterol levels depend on diet and genes, but high levels of LDL have been linked to eating lots of saturated fats and few mono/polyunsaturated fats. What is cholesterol? Cholesterol is a lipid found in cell membranes and is used in the production of hormones and bile. high-density lipoprotein (HDL): often called good cholesterol low-density lipoprotein (LDL): often called bad cholesterol. Cholesterol is transported in the blood by molecules called lipoproteins, of which there are two types:

28 © Boardworks Ltd of 36 Good and bad cholesterol How do good and bad cholesterol affect a persons health?

29 © Boardworks Ltd of 36 Excess LDL is deposited on the walls of blood vessels, which can lead to clots in the arteries. This can starve the heart of oxygen and cause heart disease. HDL returns cholesterol to the liver where it is metabolized. Cholesterol and heart disease The risk of heart disease may be reduced by: Why is LDL called bad cholesterol? Why is HDL called good cholesterol? lowering blood cholesterol eating more HDL than LDL gentle daily exercise.

30 © Boardworks Ltd of 36 Kevins blood test showed high cholesterol, but not high enough to require drug therapy to reduce it. Should Kevin buy the margarine? What extra information would help him decide? This margarine claims to cut blood cholesterol by 10%, but it costs four times as much as normal margarine. Taking action

31 © Boardworks Ltd of 36 The plant extracts in margarine that lower cholesterol are less effective than cholesterol-lowering drugs called statins. Should these drugs be available without a prescription? What do you think? No! People with normal cholesterol might take them and they wouldnt be checked for side-effects like liver damage. What are statins? Yes! People should be allowed to self-medicate.

32 32 of 36© Boardworks Ltd 2006

33 33 of 36 blood pressure – The pressure in the arteries during and between contractions of the heart. body mass index – A measure of a persons weight in relation to their height. chemical digestion – The process of breaking large food molecules into smaller ones using enzymes. fitness – Strength, stamina, flexibility, agility, speed and cardiovascular efficiency. health – Freedom from disease and injury. heart disease – An abnormal condition of the heart or the arteries that supply the heart. Glossary (1/2)

34 © Boardworks Ltd of 36 lipoproteins – Molecules that carry cholesterol in the blood and which are either high density or low density. metabolic rate – A measure of how fast chemical reactions occur in cells. obese – A person who is very overweight and has a BMI of over 30. physical digestion – The breaking up of pieces of food by chewing it in the mouth and churning it in the stomach. saturated – A type of animal fat that raises blood cholesterol levels and increases the risk of heart disease. unsaturated – A type of fat from vegetable and fish oils that helps lower blood cholesterol levels and reduce the risk of heart disease. Glossary (2/2)

35 © Boardworks Ltd of 36 Anagrams

36 © Boardworks Ltd of 36 Multiple-choice quiz


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