Unit 1 The Digestive System

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What are the seven food groups and their role in a healthy balanced diet. 2. The chemical tests to detect the presence of proteins, lipids, carbohydrates or sugar in foods. 3. What the recommended daily amounts of vitamins and minerals are in a healthy diet. 4. The role of the digestive system and its key organs during the physical and chemical breakdown of food. 5. The role of enzymes during the chemical breakdown of foods. 6. How enzymes function as catalysts. 7. The role of the villi tissue in the absorption of nutrients from the gut into the blood. 8. The fate of these nutrients in the body and their assimilation into cells and tissues. 9. The health consequences of overeating and under eating. 10. The importance of getting the balance right. Nutrition, Nutrients, Food, Groups, Fats, Carbohydrates, Proteins, Minerals, Vitamins, Fibre, Water, Digestive, System, Physical, Chemical, Villi, Breakdown, Absorption, Nutrients, Amino acids, Glucose, Fatty acids, Glycerol, Obesity & Malnutrition. web: www.science-interactive.co.uk email: sales@science-interactive.co.ukScience Interactive LTD PO BOX 50764 LONDON NW6 9AT Click mouse to begin Science Interactive LTD Copyright 2005 Overview of the digestive systemOverview of the digestive system The digestive system is a collection of cells, t________ and organs that function together to breakdown and absorb the daily essential nutrients, minerals and vitamins required for healthy growth and development. The digestive system is able to breakdown proteins, fats and carbohydrates prior to their absorption into the bloodstream. These large food molecules are broken down into smaller molecules by both physical and chemical d________. Name a cell, tissue and organ that belongs to the digestive system ? The digestive system: Anus Rectum Large Intestine Small Intestine Liver Stomach Oesophagus Mouth Organ __________________________________ ? __________________________________ ? __________________________________ ? __________________________________ ? __________________________________ ? __________________________________ ? __________________________________ ? Chews foods, using canines, incisors and molars. Function (complete table)Diagram of the digestive system Word bank: tissues digestion Science Interactive LTD Copyright 2005 Dietary intake of foodsDietary intake of foods Our dietary intake of foods like proteins, carbohydrates and lipids should provide us with the correct amount of c________ energy to maintain our daily activities, growth (if we are children) and repair. An adult male requires about 10,500 kilojoules per day, equivalent to about 100 joules per second. This is the same energy that a 100 watt light bulb uses. Taking too much energy, by perhaps consuming too much raw sugar or fat, can lead to weight gain, high blood pressure and eventually o________. Daily energy requirements: Word bank: chemical obesity Growth & reproduction Assimilation Dietary energy Respiration 10,500 kJ/day (adult male) C6H12O6 6O2 6CO2 6H2O Mitochondria Energy Respiration All the chemical energy, vitamins and minerals that we require are provided by a balanced diet. Overeating or under eating, eating too little vitamins and minerals can cause many health problems in adults and children. It is estimated that one in four adults in the Britain will be clinically obese by 2010. Notes Diagram Dietary intake, assimilation and respiration Deficiency diseasesDeficiency diseases Your diet needs to be b____________, providing all the necessary v_________ and minerals that you require for healthy growth and development. In some areas of the World, poor diets lacking in just one or two minerals or vitamins causes deficiency diseases. Scurvy is a good example of a deficiency disease that was common amongst sailors during the 17th and 18th centuries. This disease was caused by a lack of vitamin C contained in fresh fruit and vegetables, then unavailable during the long sea voyages. Scurvy can lead to bleeding of gums and the general deterioration of muscles and joints. Deficiency diseases: Science Interactive LTD Copyright 2005 Word bank: balanced vitamins Scurvy: Gums begin to bleed and old wounds begin to open. Limes were carried and included in a sailors diet to avoid scurvy. Osteoporosis: A diet lacking in calcium leads to poor teeth and bone development. In older age, bones become weak and break easily. Ricketts: A lack of vitamin D causes soft bones during a child’s growth. This disease is known as rickets. Vitamin D is produced by the skin during the summer months. Night blindness This is a result of too little vitamin A in the diet. Notes Rickets Vitamin D Night blindness Vitamin A OsteoporosisScurvyDeficiency Diagram Vitamin C Calcium Science Interactive LTD Copyright 2005 A balanced dietA balanced diet The amount of energy (kJ) we consume through our diet and the recommended daily amount of m________ and v___________ we need for normal healthy growth and development is given by the table below. Notice that these values depend on our age, our sex, when female if we are pregnant or lactating and even our lifestyles. The amount of e_______ we need can also depend on the type of job we have, for example a labourer digging roads will require more energy from their diet than someone who works in an office. Look at the information given by the table and answer the questions. Daily vitamin, mineral and energy requirements: 140001512751.36563+200035Female (lactating) 130003010700.860+ 12+ 100035Female (pregnant) 12000158600.85063975035Female 12000158600.84455975015Female 10000101060163801050035Male 120001210601.159591250015Male mgmgugmgmggkgkJYearsUnits CalciumIronVit DVit CVit AProteinBody Wt.EnergyAgeSex Word bank: minerals vitamins energy Questions: 1: Why does a 15 year old male require more energy than a 35 year old male. 2: Why do females require more iron than males. 3: What role does vitamin C and calcium play in the body. 4: Why do you require less vitamin D in the summer when compared to winter. 5: Why does a lactating female require the most protein in her diet. Science Interactive LTD Copyright 2005 Nutrition and food groupsNutrition and food groups oneone There are seven basic food groups essential for a healthy d______. The three main food groups p________, fats and carbohydrates provide us with all the energy requirements as well as having specific functions in the body. Carbohydrates should make up about 55% of your total daily kilojoule intake. Too much fat in your diet can lead to blocked a_______ and obesity. Protein is required most during p_______ in adolescents for growth and repair. Compare the diets of a body builder, adolescent female and male and a pregnant female, how might they differ ? Proteins, carbohydrates and lipids: Word bank: diet proteins arteries puberty ______________________ _____________________? ____________________ ___________________? Animal flesh, Soya bean and nuts. Sources Converted readily to glucose by carbohydrase enzymes found in mouth saliva and the small intestine. Glucose is then respired in cells. Carbohydrates Store of energy. Insulates the body against the cold. High lipid diet lead to atherosclerosis and obesity. 1 in 5 adults are obese. For growth and repair. During puberty protein demand is very high. Why do body builders take a high protein diet ? Function Diagram Proteins Lipids Science Interactive LTD Copyright 2005 Nutrition and food groupsNutrition and food groups twotwo The other four food groups, although they do not provide the body with any energy, are all essential for healthy g_______ and development. A balanced diet supplying all the necessary vitamins and minerals comes from eating a diet containing low fat meat, plenty of carbohydrates, fresh f_____ and vegetables. Many foods sold in supermarkets now have vitamins and minerals added to them, so that we can all take our recommended daily amount. Vitamins, minerals, roughage and water: Word bank: growth fruit _________________ ________________? ______________ _____________? _______________ ______________? All fresh fruit and vegetables. Sources Helps keep regular bowel movements. A low fibre diet increases the risk of contracting large bowel cancer. Roughage Correct hydration is essential for every cell and of course normal blood pressure. How much water should you drink every day ? Water Healthy tissue growth and development. A lack of iron causes anaemia of the blood. Low calcium affects bone growth. Healthy tissue growth and development. Lack of vitamins leads to deficiency diseases like scurvy and rickets. Function Diagram Vitamins Minerals Science Interactive LTD Copyright 2005 Food testsFood tests oneone The presence of proteins, starch, sugars and l_______ in foods can be tested for by using ‘food tests.’ Scientists test foods for the presence of each of these food groups so they can provide nutritional information on their food products. Where is this information normally found on a packet of crisps or a chocolate bar ? Food tests: Word bank: lipids Control Positive Control Positive Control Positive lipid food test Paper goes clear with lipidsResult Iodine test Place 6 drops of iodine water on food sample. Starch Benedict's test Add 5cm3 of benedict’s solution. Heat tube in hot water for 5 minutes. Sugar Paper test Place a small amount of tested food on paper. Allow to dry. Biuret’s test Add 5cm3 of copper sulphate and 5cm3 of sodium hydroxide. Test Diagram Protein Lipid Science Interactive LTD Copyright 2005 Food testsFood tests twotwo Starch, a polymer of g_______ is found in many foods including all cereals and most vegetables. Starch is broken down by the carbohydrase e________ to glucose. In this form, glucose is readily absorbed and transported to the many billions of cells in the body. Glucose is oxidised with oxygen during cellular respiration to provide energy essential for life. Although glucose is essential for cellular respiration, which disease might you suffer after years of eating a high glucose diet ? Testing for starch in foods: Word bank: glucose enzyme Starch ? Yes No Apple Starch ? Yes No Sucrose solution Starch ? Yes No Starch ? Yes No Results Diagram Starch solution Corn Science Interactive LTD Copyright 2005 Function of the digestive organsFunction of the digestive organs oneone Each organ or tissue in the digestive system has a specific function that helps break down the three main food groups (proteins, lipids and carbohydrates) into small molecules so they can be a_________ into the blood stream. The majority of e___________ that chemically breakdown foods are released by the pancreas into the small intestine. After carbohydrate, protein and lipid breakdown, their products; sugars, amino acids, fatty acids and glycerol are absorbed across the villi into the blood stream. Why can only small food molecules like glucose cross from the gut into the blood ? Digestive organs: Adds acid and proteases to begin protein breakdown. The stomach has a pH of around 2. This also kills any bacteria found in food. Stomach Most enzymes are found here. Lipids, proteins and carbohydrates are broken down before they are absorbed into the blood across the villi. Small intestine Sends contents to stomach by squeezing chewed food (bolus) This process is called peristalsis. Gravity also helps this process. Chews food and secretes salvia which lubricates the food and contains the enzyme carbohydrase, which begins to break down carbohydrates. Notes Diagram Teeth Food pipe Word bank: absorbed enzymes Science Interactive LTD Copyright 2005 Functions of the digestive organsFunctions of the digestive organs twotwo All nutrients including amino acids and glucose and other food groups including water, minerals and vitamins are absorbed by the v______ found in the small intestine. The remaining organs of the digestive system including the large intestine and colon remove water from undigested material, helping to form a solid stool. The rectum stores the waste faeces until its excretion via the anus. Blood takes the nutrients to the l_______ where they are processed and sent via the circulatory system, the billions of cells in the human body. Digestive organs: The large intestine absorbs and recycles water. The stool begins to become solid. This makes it easier to store by the rectum. Large intestine The rectum stores the solid waste which contains undigested food (fibre), bacteria, water and broken down blood cells. Rectum and anus The pancreas is found behind the stomach. The pancreas makes and releases all the enzymes found in the small intestine. Processes all nutrients like amino acids, glucose, fatty acids and glycerol. Also breaks down excess amino acids forming urea. Notes Diagram Liver Pancreas Word bank: villi liver Science Interactive LTD Copyright 2005 Physical digestionPhysical digestion The breakdown of proteins, carbohydrates and lipids begins with chewing. Humans have a mixture of c_______, incisor and molar teeth which are designed to cope with a varied diet, which includes animal flesh and vegetables. Our canines and incisors tear and rip food. Our molars, with their flat profile are designed to grind and chew fibrous vegetable matter like root vegetables and fruits. How does a high sugar diet affect our teeth and lead to tooth decay ? Human teeth and physical digestion: Word bank: canine Modern toothpaste now contains fluoride which helps control oral bacteria and prevents tooth decay. Always have a 6 monthly check-up at the dentist. Brushing The tooth (incisors, canines and molars) are capped with white enamel. This is made from calcium carbonate and is the hardest substance in the body. It can be eroded by acids found in foods or produced by oral bacteria. Humans have two sets of teeth. Your milk teeth are replaced when you are about eight years old. Your final molars appear in your twenties. Notes Diagram Teeth Human teeth Science Interactive LTD Copyright 2005 Enzymes and chemical digestionEnzymes and chemical digestion Digestive enzymes break down large f_____ molecules into smaller ones. Enzymes are all proteins, and are very specific, only having one substrate like a protein or a lipid. They behave like c_________, able to speed up the rate of reaction and can be recycled by the digestive system. There are three main types of enzymes found in the digestive system: proteases, carbohydrases and lipases. Look at the table below to find out the function and location of each type ? Types of digestive enzymes: Word bank: food catalysts lipases Fatty acids and glycerolSugarsAmino acidsProducts L_________ -pancreatic Lipids Carbohydrases -salivary -pancreatic Proteases -stomach -pancreatic Enzymes Diagram Proteins Carbohydrates Science Interactive LTD Copyright 2005 How enzymes functionHow enzymes function oneone For proteins, lipids and c____________ to be absorbed from the small i_________, into the blood, they must be broken down into small molecules. Digestive enzymes breakdown food chemically. An enzyme’s substrate will bind to the enzyme’s a_________ site where chemical bonds are broken producing smaller molecules which can then be absorbed into the b________ stream. How enzymes break down food molecules: Word bank: carbohydrates intestine active blood Substrates Products Substrate Enzyme substrate complex Products Enzyme (catalyst) active site Enzyme active site Enzyme (can be reused) active site Step three New products like glucose are formed which then leave the enzyme’s active site. Stage three Step two Chemical bonds are broken by the enzyme to form monomers. Step one Substrates like proteins, carbohydrates and lipids bind to the enzyme’s active site. Notes Diagram Stage one Stage two Science Interactive LTD Copyright 2005 Enzyme are biological catalysts which will increase the rate of b__________ of proteins, carbohydrates and lipids without be used up themselves. Enzyme catalysts are able to lower the activation energy required for new products like sugars and amino acids to be produced from substrates like carbohydrates and proteins. The reaction takes place in an area of the enzyme which is called the active site. Enzymes as biological catalysts: How enzymes functionHow enzymes function twotwo Lower the activation energyNot used up during the reaction Enzymes are biological catalystsCarbohydrases, Lipases, Proteases Word bank: breakdown active site active site Carbohydrase + Carbohydrate Catalyst Catalyst Carbohydrase + sugar molecules Carb ohy drat e Sugar Sugar Sugar Sugar Sugar active site active site Enzyme Enzyme Notes Diagram Substrates like carbohydrates collide and temporarily bind to the enzyme’s active site on its surface. The bonds in the substrates are weakened by the enzyme. The bonds are broken and new products are formed. These products (sugar) then leave the enzyme’s active site, leaving the enzyme catalyst unchanged and able to participate in further reactions. Breakdown of carbohydrates by carbohydrase A human body contains many hundreds of different enzymes found inside cells and as part of the d_________ system. Without enzymes, which catalyse the breakdown of nutrients l