The Digestive System PDF

The Digestive System Nutrition We take in, breakdown and use food that we eat in a process called Nutrition. Nutrients There are 6 main types of nutrients in food. 1. Carbohydrates 2. Fat 3. Protein 4. Minerals 5. Vitamins 6. Water Why do we need food? 1.Energy 2.Growth & Repair 3.Protec...

The Digestive System Nutrition We take in, breakdown and use food that we eat in a process called Nutrition. Nutrients There are 6 main types of nutrients in food. 1. Carbohydrates 2. Fat 3. Protein 4. Minerals 5. Vitamins 6. Water Why do we need food? 1.Energy 2.Growth & Repair 3.Protect against diseases  Why do we need food? Nutrient/Food Type Carbohydrate - Starch Brown bread, Energy pasta, rice, potatoes Sugar fruit Energy Fibre Fruit, cereal, Prevents vegetables, constipation Fat Vegetable oils, Energy, cell oily fish membranes Protein Lean meat, Growth, repair poultry, fish, of tissue beans, lentils, Nutrient/Food Source Function in body Deficiency Disease Type Vitamins Vitamin C Citrus fruits, kiwi, Scurvy blackcurrants Vitamin D Sunlight, dairy Rickets foods, Minerals Calcium Dairy foods, tinned Strong bones and Osteoporosis fish teeth iron Red meat, green Needed for Anemia vegetables, hemoglobin in the blood Water Maintains body temperature at What is a balanced diet? A balanced diet contains the correct amount of each of the different types of nutrients. Sugars Starch White starchy foods can be quickly changed into sugars whereas wholegrain foods contain more fibre, vitamins and minerals and we digest them more slowly.  Fibre We cannot digest fibre. Plant cell walls are made up of cellulose which humans cannot digest. The undigested fibre (roughage) helps to keep food moving along the digestive system. Fibre helps us maintain a healthy digestive system. Wholemeal bread, fresh fruit and vegetables are all high fibre foods which are good for us.  https://www.youtube.com/watch?v=JLzX_KSrxDc  Human Nutrition involves five stages 1.Ingestion – is the taking in of food into the mouth. 2.Digestion – is the breaking down of food into smaller soluble pieces. 3.Absorption – is the movement of food into the bloodstream. 4.Assimilation – is the use of the small soluble pieces of food for energy, growth and repair. 5.Egestion – the getting rid of food that we The Digestive System Oesphagus Stomach Liver Pancreas Large Intestine Small Intestine Appendix The Mouth Teeth break down food into small pieces Salivary glands make saliva. Chewed food gets mixed with saliva Saliva contains enzymes, which start to digest starch to sugar  Types of Teeth 1. Incisors – Cutting food 2. Canines – tearing food like meat and crunchy vegetables 3. Pre-molars – tear, crush and grinding food 4. Molars – chewing, crushing and grinding food Teeth Canines Four types of teeth: 1. Incisors Incisors 2. Canines 3. Pre – Molars 4. Molars Premolar Molar Location of Teeth Incisors Canines Canines Pre - Molars Pre - Molars Molars Molars Tooth Structure Main parts of a tooth 1. Enamel – a very hard substance which protects the tooth. 2. Dentine – a bone like substance 3. Pulp Cavity – contains living cells and blood supply and nerves. 4. Cement – protects the root from damage.  Biting Grasping and and Cutting Tearing Incisor Canine Grinding Grinding and and Crushing Crushing Pre - Molar Molar The Oesphagus Passes food down to your stomach The oesophagus has circular muscles in its wall These muscles Oesphagus 25 cm contract and long squeeze in behind the food to push it along The Stomach Muscular bag that holds 2 litres of food Secretes hydrochloric acid Makes digestive juices Muscular walls churn the food making sure it’s all mixed After 2-3 hours churning it’s a runny liquid The Liver Bile is produced by he liver. Bile breaks down fats. Bile is stored in the gall bladder. After food has been absorbed into the blood, the food is taken to the liver The liver processes some of it, before it goes any further The food dissolved in plasma is the taken to other parts of the body Pancreas Leaf – like structure Produces digestive enzymes e.g. amylase Passed in Small Intestine and helps in the digestion of food Helps control blood sugar The Small Intestine Actually 6 m long! Plays important roles in digestion and absorption Two important liquids are added here: Pancreatic juices Bile 90% of food is digested and absorbed here! The Large Intestine Shorter but wider than small intestine Absorbs water from food Passes water into the blood Mainly fibre, dead cell, bacteria and water reach here! OB8 – Investigate the action of amylase on starch; identify the substrate, product and enzyme  An enzyme is a biological catalyst – speeds up chemical reactions inside cells Without Catalyst With Catalyst Enzymes Proteins found in every cell of the body Digestive enzymes – involved in breaking down food Amylase in Saliva Amylase breaks starch down into Maltose http://subscription.echalk.co.uk/ index.htm How Enzymes Work Substrate Enzyme Product Amylase Digestion Absorption Starch Glucose Intestinal wall OB8 - Investigate the Action of Amylase on Starch Thermometer 37oC for 10 minutes Test tube Beaker Water Wire Gauze Bunsen Burner Tripod Stand OB8 - Investigate the Action of Amylase on Starch Starch not broken Starch broken down down Tube A Tube B Iodine Starch Soln. Starch Soln. + Water + Amylase To Show that Amylase Breaks Starch into Glucose No Glucose Glucose Present Present Tube D Tube C Benedicts Solution Starch Soln. Starch Soln. + + Water Amylase Test for Glucose Benedicts Solution Positive Negative Test Yourself! Oesphagus 1 2 Stomach Liver 3 Pancreas 4 Large 6 Intestine 5 Small Intestine Appendix 7 Facts for the Curious! What is added to the food each day as it passes through the gut……. In mouth: saliva = 1 litre In stomach: acid & enzymes = 1 litre In intestines: bile from liver = ¾ litre, pancreatic enxymes = ¾ litre, intestinal enymes = ½ litre Total: 4 litres!! Facts for the Curious 70 year olds only produce about half the amount of enzymes that they produced when they were 20! JOBS OF THE DIGESTIVE SYSTEM ORGANS How many parts of the digestive system can you label? Do you know what the function of each part is?