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Digestive system

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  1. Digestive system http://www.mennellmedia.co.uk/VideoProjects/ToiletTales/ToiletTales.html

  2. H&W Outcome I am developing my understanding of the human body and can use this knowledge to maintain and improve my wellbeing and health. HWB 3-15a / HWB 4-15a H&W Throughout this unit, the following Health and Wellbeing learning outcome will be covered in great detail:

  3. Starter – Answer on boards Why do we need food?

  4. Lesson 4 – Learning outcomes Know the main food groups and their functions Know how to carry out food tests for starch, sugar and protein Examine food labels to identify which food groups are present in different foods

  5. H&W Why do we have to eat? • We have to eat to stay alive. Everybody knows that. • Food is your body’s fuel. It supplies the energy to keep your body working. • But food has other important jobs to do. Can you think of anything else that your food is needed for? Think for 1 minute, discuss with a partner for 1 minute, then share ideas with your group. • Copy the heading, and write a sentence to describe three things that our food is used for.

  6. H&W Chemicals in food Our food is a mixture of many different chemicals. These food chemicals can be split into groups. The three major groups are: • Carbohydrates (starch and sugars) which are used for energy. • Fats which are also for energy. • Proteins which are used for growth and repair of cells and tissues. As well as these, our food also contains very small quantities of vitamins and minerals for health, fibre to keep food moving through the gut, and water for chemical reactions.

  7. H&W Food Groups

  8. Food tests • We can test food to find out what food chemicals it contains. • Your teacher will demonstrate how to do 3 different food tests. • You will then test some foods to see what they contain.

  9. Food tests • TEST FOR GLUCOSE (SUGAR) 1. Add blue Benedict’s solution to the food in a test tube. 2. Heat in a beaker of boiling water for 5 minutes. 3. The solution turns to green or orange if glucose is present. NEGATIVE RESULT(Blue) POSITIVE RESULT(Orange)

  10. TEST FOR STARCH • Put a small amount of food in a dimple in a spotting tile. • Add iodine solution. • If the solution turns black, starch is present. This is a negative result for starch This is a positive result for starch

  11. TEST FOR PROTEIN • Mix the food with water in a test tube. • Add Biuret solution. • If the solution changes to purple, protein is present. Negative result for protein Positive result for protein

  12. Food tests summary COPY TEST FOR GLUCOSE (SUGAR) • 1. Add blue Benedict’s solution to the food in a test tube. • 2. Heat in a beaker of boiling water for 5 minutes. • 3. The solution turns from blue to green or orange if glucose is present. TEST FOR STARCH • Put a small amount of food in a dimple in a spotting tile. • Add iodine solution. • If the solution turns from orange to black, starch is present. TEST FOR PROTEIN • Mix the food with water in a test tube. • Add Biuret solution. • If the solution changes from blue to purple, protein is present.

  13. What to do • Collect a food sample from your teacher. • Test the food for - glucose by heating with Benedict’s - starch by adding iodine in a spotting tile - protein by adding water then Biuret • Record your results in the table. • Collect another food and repeat.

  14. COPY Food tests results if present x if absent

  15. Food Testing

  16. Food tests - conclusion • Write one or two sentences to summarise what you found out. • Collect some food labels, and study the ‘Nutritional Information’. Look at the values for ‘per 100g’. • Make three lists as shown below and write the names of foods in the correct list. Foods high inFoods high inFoods high in carbohydratesfatprotein Food detective game ‘Food and drugs’ animation and quiz

  17. Test your knowledge 4 • Name the food group that is needed for growth and repair. • Name the two types of carbohydrates. • What are fats used for in the body? • What chemical is used to test for starch? • What colour does Biuret turn if protein is present? • Name two foods high in protein. • Other than carbohydrate, protein and fat, name two other components of a healthy diet. ANSWERS ON NEXT SLIDE

  18. Answers • Protein • Starch and sugar • Energy • Iodine • Blue to purple • Meat, fish, eggs, nuts, beans. • Vitamins, minerals, fibre, water.

  19. H&W Lesson 5 – Learning outcomes • Know that the energy value of different foods varies • Carry out an experiment to compare the energy value of different foods • Know the structure and function of the digestive system

  20. H&W Energy in foods • Know that the energy value of different foods varies

  21. COPY H&W Energy content of food • It’s a fact! Some people really do need to eat more food than others. (Why do you think this is? Discuss with a partner.) • It depends on a number of factors like your age, your size and how active you are. • Different foods give you different amounts of energy. The energy value in food is measured in kilojoules (kJ).

  22. COPY AND COMPLETE H&W Energy content of food • Study the ‘Nutritional information’ on 6 food labels, and find the energy in ‘kJ per 100g’. • Copy and complete the table.

  23. H&W Typical information that you would see on a food label You may see this label Information is given on food labels to help promote a balanced diet

  24. Comparing energy content of foods • You can estimate the energy content of a food by burning it. • When it burns, the chemical energy in the food is converted to heat and light energy. • If we measure how much heat is given off, we can compare different foods to find out which has most energy.

  25. Design the experiment • With a partner, discuss how you could set up an experiment to compare the energy in sugar, flour and rice. • Please note - you cannot put a thermometer into a flame! • Make brief notes of your ideas. Draw a diagram to show how the apparatus will be set up. • Think about what will need to be kept the same each time to make it a fair test. • List any safety precautions that will be needed. • Discuss your ideas with your teacher.

  26. Do the experiment • Here is one method to do this experiment which you could use. thermometer boiling tube with cold water Deflagrating spoon Set fire to food in a bunsen burner, then quickly place spoon under boiling tube Clamp stand Burning food


  28. COPY AND COMPLETE Conclusion • The food with the highest energy content was ___________. I knew this because it released the most ________ energy.

  29. Digestive system • Food has to get into the bloodstream to be delivered to all cells of the body • First it has to be broken down or digested so that the molecules are small enough to be absorbed through the wall of the intestine and transported in the blood. • The digestive system is a series of organs which chemically break down the food into small soluble molecules. • This chemical breakdown is carried out by digestive juices released into the mouth, stomach and small intestine.

  30. Digestive system salivary glands mouth Your teacher will show you the organs of the digestive system on a ‘Model Body’. Use this diagram to help you to label the handout sheet on the Human Digestive System. Then stick the sheet into your notebook. gullet liver stomach gall bladder pancreas large intestine small intestine appendix rectum anus

  31. http://kidshealth.org/kid/htbw/digestive_system.html This web site has a digestive diagram click on it . You can move your cursor over the diagram and an explanation appears http://monarchcenters.wikispaces.com/Digestion+Overview This is a animation of how different foods would be digested.

  32. Test your knowledge 5 1. Put these organs in the order that food passes through them : small intestine, gullet, mouth, large intestine, anus, rectum, stomach 2. Name two factors which affects how much energy you need in a day. ANSWERS ON NEXT SLIDE

  33. Answers • Mouth, gullet, stomach, small intestine, large intestine, rectum, anus. • Your age, body size, activity.

  34. Lesson 6 – Learning outcomes • Know the role of enzymes in digestion • Carry out an experiment to demonstrate the action of an enzyme Digestion video clip

  35. COPY Digestive enzymes • Digestive juices released into the mouth, stomach and intestines contain enzymes which chemically break down the food. • There are many different enzymes each of which breaks down a different type of food. • One of these enzymes is amylase. It breaks down starch, a large molecule, into smaller sugar molecules.

  36. COPY Digestion experiment Aim : to find out the effect of amylase on starch Thermometer Water at 37°C 10ml starch + 2ml distilled water 10ml starch + 2ml amylase

  37. Method • Prepare a beaker of water at 37°C using kettle and tap water. • Add 10ml starch solution to two boiling tubes. • Add 2 ml water to one and 2ml amylase to the other. • Place both test tubes in the beaker of water. • Immediately stir then remove a drop from each test tube and put on separate dimples on a spotting tile. • Add iodine to both samples. • After 10 minutes repeat steps 5 and 6.

  38. Method : Now write a brief outline of the method you used in your own words. Remember to mention all the equipmentyou used and the volumes you measured. Results • Copy and complete the table.

  39. COPY AND COMPLETE Conclusion amylase • The enzyme _________ breaks down ______ into sugar. starch Answers

  40. Test your knowledge 6 • Answer these questions in sentences • Why was the test tube with starch and water used? • Why were the test tubes placed in water at 37°C? • Why must starch be broken down in the digestive system? ANSWERS ARE ON THE NEXT SLIDE

  41. Answers • 1. To compare to the experiment / to prove that amylase is needed to break down starch / as a control experiment • 2. To create the same temperature conditions found in the human body • 3. To produce small molecules that can be absorbed and transported in the blood

  42. Lesson 7 – Learning outcomes • Know what happens to digested food and undigested food • Know what is meant by a balanced diet • Study your own diet to assess whether it is healthy

  43. What happens to digested food? COPY • After digestion, all the simple food chemicals are absorbed through the wall of the small intestine into the blood. The blood then delivers the digested food to all our cells. small intestine

  44. COPY What happens to undigested food? • Excess water is absorbed from the waste into the blood by the walls of the large intestine. • The solid waste is now called faeces. It is stored in the rectum and passes out of the body via the anus. • Food which cannot be digested is passed to the large intestine. Diagram of large intestine

  45. H&W Healthy Diet • To remain healthy, it is important to have a balanced diet. • This means eating the right quantities of each of the food groups. • Too much of one group, or not enough of one group, may lead to: - becoming overweight or underweight - children not growing properly - having less resistance to disease - poor functioning of the body organs and systems (eg the brain, kidneys, liver etc)

  46. H&W My Day’s Diet This is what I had to eat and drink yesterday. Your teacher will hand out this sheet to be completed in class.

  47. H&W COPY AND COMPLETE This is what I think about my day’s diet. Overall, do you think your diet was good or bad ? Explain your answer.

  48. Test your knowledge 7 1. Which of these statements is true? A balanced diet is a. eating equal amounts of all the main food groups b. eating the right amount of all the main food groups c. eating five portions of fruit and vegetables a day • State two possible outcomes of someone not eating a balanced diet. 3. What is absorbed through the wall of the small intestine? 4. What is absorbed through the wall of the large intestine? ANSWERS ON THE NEXT SLIDE