Human Nutrition Notes 2025 PDF

HUMAN NUTRITION, DIGESTION, MALNUTRITION AND TRADITIONAL FOODS « NOTE: you will need the Grade 10 and Grade 11 eBook for this section. Check what you already know – do Activity 1 on page 111 in Grade 11 eBook 1. Why do we need food? Nu...

HUMAN NUTRITION, DIGESTION, MALNUTRITION AND TRADITIONAL FOODS « NOTE: you will need the Grade 10 and Grade 11 eBook for this section. Check what you already know – do Activity 1 on page 111 in Grade 11 eBook 1. Why do we need food? Nutrition can be classified either as autotrophic or heterotrophic. Using the diagram below write a definition for: Autotroph Heterotroph Page 112 & 113 in Grade 11 eBook. Discuss animal diet groups. 1  Balanced diets Eating a healthy, balanced diet is an important part of maintaining good health. You are what you eat and what you eat impacts everything in your body and how it functions. This means eating a wide variety of foods in the right proportions. According to the United Kingdom National Health Service (NHS), in order to have a healthy, balanced diet, people should try to: eat at least 5 portions of a variety of fruit and vegetables every day (5 a day). base meals on higher fibre starchy foods like potatoes, bread, rice or pasta. have some dairy or dairy alternatives (such as soya drinks). eat some beans, pulses, fish, eggs, meat and other protein. choose unsaturated oils and spreads, and eat them in small amounts. drink plenty of fluids (at least 6 to 8 glasses a day). Food and drinks high in fat, salt and sugar are meant to be consumed less often in small amounts. Fruits and vegetables are a good source of vitamins and minerals and fibre. They should make up just over a third of the food your eat each day. It is recommended that you eat at least 5 portions of a variety of fruits and vegetables every day. A portion is: 80g of fresh, canned or frozen fruit and vegetables 30g of dried fruit – which should be kept to mealtimes 150ml glass of fruit juice or smoothie – but do not have more than 1 portion a day as these drinks are sugary and can damage teeth Just 1 apple, banana, pear or similar-sized fruit is 1 portion each. A slice of pineapple or melon is also 1 portion, and 3 heaped tablespoons of vegetables is another portion. Activity: Keep track of what you have eaten for a day (breakfast, lunch, supper, snacks & drinks). Compare your diet to the Healthy Eating Plate on the following page: 2 There are some important nutrients which are found in food. (watch Twig video on a balanced diet) Different diets: Food Allergies and intolerances – such as dairy free, fish and shellfish allergies, nut free and gluten free, celiac disease. Special dietary requirement – such as vegetarian, vegan, pregnancy. Religious – such as Halaal and Kosher. Weight-loss trends – such as Atkins diet, Paleo diet, Ketogenic Diet, Banting Diet, Intermittent Fasting, 3  1. Complete the table below Two foods in this group Function or importance Carbohydrates Fats Proteins Vitamins A B C D E Minerals: Calcium Phosphorous Iron Iodine Magnesium Do activity 5 page 129 from Grade 11 eBook 4  Molecules for Life Grade 10 eBook page 3 Do activity 1 to see what you know. All molecules & compounds are classified as organic or inorganic. Organic compounds always contain the elements carbon and hydrogen. Sometimes they contain oxygen and nitrogen. Examples: Proteins, Carbohydrates, Lipids Inorganic compounds are not made up mostly of carbon and hydrogen together but combinations of other elements. Examples: Water, minerals Hydrolysis and Condensation synthesis Hydrolysis – means ‘using water to split’ so water is added to a reaction Condensation – water is produced from a reaction Hydrolysis Condensation 5 Organic Compounds: Carbohydrates Made up of Carbon, Hydrogen and Oxygen. The hydrogen and oxygen are always in a ratio of 2:1. The general formulae for a carbohydrate is CnH2nOn If Glucose has 6 carbons, write the chemical formulae for glucose: _________ Monosaccharides are simple sugars e.g. glucose, fructose, galactose Disaccharides are made up of 2 monosaccharides e.g. maltose (glucose + glucose) lactose (glucose + galactose) sucrose (glucose + fructose) Polysaccharides are insoluble e.g. starch, cellulose, glycogen Watch the following clips http://ed.ted.com/lessons/sugar-hiding-in-plain-sight-robert-lustig https://www.twig-world.com/film/food-basics-carbohydrates-1379/ Protein (*Also see page 38 of these notes) Protein consists of Carbon, Hydrogen, Oxygen and Nitrogen. They can sometime contain sulphur and phosphorous. Acid group Amino group (NH2) containing Nitrogen (do not learn this diagram) The monomers (building blocks) of protein are amino acids. There are approximately 20 known natural amino acids which are manufactured by plants. E.g. glycine, alanine, cysteine. Plants produce the glucose during photosynthesis and then absorb nitrogen, sulphur and phosphorous from the soil to produce amino acids. 6  Amino Acid Di-peptide Tri-peptide Polypeptide – less than 50 amino acids. Protein more than 50 amino acids. Your body is capable of sequencing amino acids to produce proteins. This happens at the ribosomes. It is very important that the sequence is done correctly because if one amino acid is out of place it could result in a mutation (change in the genetic material) and your body not being able to function properly. (Similar to a letter in the incorrect place in a word) Proteins have a very specific structure. This structure can be destroyed by high temperatures (denaturation) and incorrect pH (inactive). If the structure is destroyed the protein loses its ability to function. This relates to the functioning of enzymes and hormones. All enzymes and most hormones are proteins. Watch: https://www.twig-world.com/film/food-basics-proteins-1381/ Lipids (Fats and Oils) Fats are from animal sources and are solids at room temperature. Oils are from plant sources and are liquids at room temperature. These are much healthier for you. Fats and oils are made up of carbon, hydrogen and oxygen. Similar to carbohydrates but the hydrogen and oxygen are not in a ratio of 2:1. Lipids release more energy than carbohydrates because of this but because it is so difficult to break down a fat it is not the primary energy source. Lipids are made up of two important building blocks: 1 glycerol and 3 fatty acids 7 Lipids can be saturated with hydrogens which means that it has its total number of hydrogens. If a fat is unsaturated (poly or mono) it does not have its total number of hydrogens. Lipids are insoluble in water but are soluble in alcohol. Watch: https://www.twig-world.com/film/food-basics-fats-1380/ « Complete page 36 of these notes as a summary of the organic compounds, including the functions. 8  Food tests – practical involving mystery foods. You did some of these tests in Grade 9. Using you Grade 10 eBook page 6, 8 & 9 read through the food tests for glucose, starch, fats and proteins Nutrient / food Method Result – positive colour change Starch Place food in Petri dish. Colour change: Add 2 -4 drops of iodine on food brown to blue/black stuff. Glucose Add food to test tube. Add 10 drops Colour change: of water and 10 drops Benedict’s blue to red/brown solution. Heat in a hot water bath. Protein Pour item into test tube. Add 10 Colour change: (BIURET TEST) drops NAOH and 10 drops CuSO4. blue to purple= protein present blue to pink = polypeptide present Sucrose Add HCL to sucrose solution, heat, Colour change: add Benedict’s solution, heat blue to red/brown Glucose Add item to test tube. Add water, add Colour change: (additional test) an equal amount of Fehlings A and B, blue to red/brown heat Lipid/fat/oil Grease spot test: dissolve in Grease spot left on filter paper ethanol/ether, pour onto filter paper, in circled area draw a circle around the spot, shake the paper at an open window, ethanol evaporates. (for a control drop some ethanol on the filter paper too in a separate spot and draw a circle around it) Cellulose Place item on petri dish. Drop one or Colour change: Brown to two drops of Schulz’s solution blue/black NB! When working with powders mix with a little water and when working with food products you will need to grind them up with a pestle and mortar. 9  Functions of the digestive system Use the diagram on p 116 of the Gr 11 eBook to complete the following definitions: - Ingestion: Digestion: Absorption: Assimilation Elimination/egestion: Food must be broken up by the digestive system for it to be absorbed. There are two types of breakdown: Mechanical digestion: Chemical digestion: Digestive system Use the diagram on pg 114 of Grade 11 eBook to learn each organ and its function. « Complete table on page 34 and 35 of these notes Watch: https://www.youtube.com/watch?v=Og5xAdC8EUI&list=PLcJtKRgyQGt XW5gfvwg33DzDopFvVx4rw https://www.twig-world.com/film/introduction-to-digestion-1014/ 10 11 We are going to look at some organs and their functions in more detail: Refer to Gr 11 eBook page 117-118 Ø Mouth Used for swallowing, chewing (mechanical process) and the production of saliva. Saliva is the first digestive juice food comes into contact with and it contains an enzyme. An enzyme assists the breakdown process from large molecules into smaller ones. Enzymes are sensitive to temperature and pH and specific to the substrate they break down. This particular enzyme, salivary amylase, found in saliva, breaks down starch. It works in a neutral/alkaline medium and at body temperature. What is the importance of the tongue? What is the purpose of chewing? What is swallowing? What is the epiglottis? What happens if this does not close? 12 Extension: The formula for teeth in the human mouth is 2.1.2.3 2.1.2.3 Explain what this means: 13 Reading extension: What is tooth decay? Tooth decay is damage to a tooth's surface, or enamel. It happens when bacteria in your mouth make acids that attack the enamel. Tooth decay can lead to cavities (dental caries), which are holes in your teeth. If tooth decay is not treated, it can cause pain, infection, and even tooth loss. What causes tooth decay? Our mouths are full of bacteria. Some bacteria are helpful. But some can be harmful, including the ones that play a role in tooth decay. These bacteria combine with food to form a soft, sticky film called plaque. The bacteria in plaque use the sugar and starch in what you eat and drink to make acids. The acids begin to eat away at the minerals on your enamel. Over time, the plaque can harden into tartar. Besides damaging your teeth, plaque and tartar can also irritate your gums and cause gum disease. NIH: National Institute of Dental and Craniofacial Research Ø Oesophagus Peristalsis takes place in the oesophagus (and also large and small intestine) Write a brief explanation below about how this process occurs. Use the diagram below & your iPads to research this process. Write 5 points to summarise this process: Extension: What is gastro-oesophageal reflux? 14 Ø Stomach It is involved in churning (physical process) up the food by muscular movement. Food is mixed with gastric juices (contain protein enzyme) and hydrochloric acid (provides the correct pH for enzymes to function). This makes up chyme. Why is the stomach well adapted to churn the food? Put these three diagrams in order. Watch: https://www.twig-world.com/film/stomach-1015/ 15 Ø Small intestine Divided into 3 sections: 1) Duodenum (1st section after the stomach which assists in chemical digestion) 2) Jejunum (most absorption occurs here) 3) Ileum (where the remainder of nutrients are absorbed) Slowed peristalsis (mechanical process) in the small intestine and increased surface area, by means of villi, allow for a large amount of absorption. Watch: https://www.twig-world.com/film/small-intestine-1017/ Absorption *Grade 11 eBook page 121 - 123 16 micrograph of the villi (with microvilli) in the small intestine 17  18 Try to label the diagram alongside without looking back  « Describe 5 ways in which the villi are adapted for rapid absorption of substances into the blood: 1. 2. 3. 4. 5. 19 Ø Large intestine Also known as the bowel or colon. Water is absorbed here and the remaining waste material is stored as faeces in the rectum before being removed by defaecation through the anus. Watch: https://www.twig-world.com/film/large-intestine-1018/ Ø Accessory organs (see diagram on the next page) Liver Functions include: 1. Produces bile – this emulsifies fats (makes smaller droplets to increase the surface area for lipase to work effectively) 2. Stores excess glucose as glycogen 3. Breaks down excess amino acids by the process of deamination. 4. Detoxifies the blood of poisons and toxins eg. Drugs & alcohol 5. Plays a role in metabolism Watch: https://www.twig-world.com/film/factpack-the-liver-1082/ Gall bladder Stores bile produced by the liver Pancreas (discussed later under sugar control) 20 Label and annotate (add functions) the diagram below. Refer to pages 36 & 37 of these notes and page 114 in Grade 11 eBook. 21 Detoxify 22  Enzymes *Grade 11 eBook page 119 Enzymes are proteins that control reactions necessary for cell metabolism. Watch: https://www.twig-world.com/film/factpack-enzymes-1048/ Cell metabolism refers to all the chemical reactions that occur within a living cell including: 1) Anabolism - reactions that build up compounds eg. muscle growth. Requires energy 2. Catabolism - reactions that break down compounds. Eg. cellular respiration. Releases energy FUNCTIONS OF ENZYMES: 1. Enzymes act as biological catalysts which speed up the rate at which chemical reactions occur without being destroyed in the process. Therefore, the reaction is faster. 2. The energy required to start a chemical reaction (activation energy) is less when an enzyme is present. Therefore, reactions can occur at a lower temperature. See alongside for the cellular respiration reaction: 23 3. Enzymes can be re-used because they are neither changed nor destroyed during the reaction. 4. Enzymes catalyse the following reactions (among others) 4.1 The digestion of fats, carbohydrates and proteins. 4.2 Photosynthesis and Respiration. CHARACTERISTICS OF ENZYMES: 1. Enzymes are specific in their reactions. The lock and key-mechanism describes the way enzymes work: a. Each enzyme has a specific shape. b. The form of the substrate (the substance on which the enzyme is going to act.) fits into the enzyme. c. When the reaction is completed the enzyme is released to catalyse another reaction. 24 2. Enzymes are sensitive to temperature. 1. At low temperatures enzymes are inactive and do not function efficiently. 2. The normal body temperature of humans is about 36.5 oC. 3. Human body enzymes function optimally at between 37- 40 oC. 4. At high temperatures enzymes are denatured - they are proteins. High temperatures change their shape and therefore they lose their function. 3. Enzymes are sensitive to change in pH. a. The pH of a solution describes how acid/alkaline it is. 1 7 14 Acid neutral alkaline b. Enzymes work at very specific optimum pH levels: Enzymes from STOMACH - acid medium (pH 2-3) Enzymes of DUODENUM - alkaline medium (11-13) Salivary amylase (MOUTH) - neutral medium (7) c. If enzymes are placed in solutions of a different pH to their optimum, they are denatured (their structure changes) and cannot perform their functions. 25  How is oil transported in the body? Have you ever tried to mix oil and water together? What do you observe? If you add Sunlight liquid to the oil and water mixture, what do you observe? Bile emulsifies fat. Bile is produced by the liver and stored in the gall bladder. Bile is not an enzyme as it does not digest. However, emulsification is when fat globules in the duodenum are broken into tiny droplets, which provides a larger surface area on which the enzyme lipase from the pancreas, can act to digest the fats into fatty acids and glycerol. 26  Problems associated with nutrition Recap malnutrition from grade 9 (watch Twig video on malnutrition) Malnutrition is when a balanced diet is not consumed (an incorrect diet is followed) and a person may lack a specific food group in their diet and therefore suffer from a nutritional deficiency disease. Examples: Rickets – lack of __________________ Scurvy – lack of ___________________ Kwashiorkor – lack of _______________ Marasmus – lack of ________________ Beri-Beri – lack of _________________ Aneamia – lack of __________________ Goitre – lack of __________________ What other examples of malnutrition do you know? Why do young adults develop eating disorders? http://www.ulifeline.org/articles/400-eating-disorders-why-do-they-happen Eating disorders, including anorexia nervosa and bulimia nervosa, are complicated, serious and potentially devastating. They’re caused by a complex combination of factors, including genetic, biochemical, psychological, cultural and environmental. While researchers haven’t been able to pinpoint the specifics behind these causes, they can identify various factors that make individuals susceptible to eating disorders. There are many misconceptions in our society about what causes eating disorders. Eating disorders are rarely about food or wanting to be thin. Instead, sufferers use food and unhealthy behaviours like dieting, starving, bingeing and purging to cope with unpleasant and overwhelming emotions and stressful situations. At least in the short term, these behaviours relieve anxiety and stress. Long term, however, they actually increase anxiety and stress and create other serious complications. Eating disorders are illnesses, not character flaws or choices. Individuals don’t choose to have an eating disorder. You also can’t tell whether a person has an eating disorder just by looking at their appearance. People with eating disorders can be underweight, normal weight or overweight. It’s impossible to diagnose anyone just by looking at them. While no one thing causes eating disorders, here are some of the factors that may contribute to the problem: Genetics Genetics has a significant contribution and may predispose individuals to eating disorders. Researchers have found that eating disorders tend to run in families. Also, there seem to be higher rates of eating disorders in identical twins than in fraternal twins or other siblings. In addition, specific chromosomes have been linked to both bulimia and anorexia. 27 Biochemistry Individuals with eating disorders may have abnormal levels of certain chemicals that regulate such processes as appetite, mood, sleep and stress. For instance, both people with bulimia and anorexia have higher levels of the stress hormone cortisol. Some research also suggests that individuals with anorexia have too much serotonin, which keeps them in a constant state of stress. Psychology Various psychological factors can contribute to eating disorders. In fact, eating disorders are common in individuals who struggle with clinical depression, anxiety disorders and obsessive-compulsive disorder. Other factors include: Low self-esteem Feelings of hopelessness and inadequacy Trouble coping with emotions or expressing your emotions Perfectionism Impulsivity Culture Dieting, body dissatisfaction and wanting to be thin are all factors that increase the risk for an eating disorder. Unfortunately, our society encourages all three. You can’t walk by a cash register without seeing a magazine that encourages rapid weight loss, calorie counting or feeling guilty after a meal. Here are some aspects of our culture that contribute to eating disorders: An over-emphasis on appearance, at the expense of more meaningful attributes Societal beauty standards that promote an unrealistically thin body shape Associating thinness with positive qualities like attractiveness, health, success and love Media’s focus on dieting and striving for a slim and toned silhouette Messages that perpetuate a fear of fat and food; viewing fat as undesirable or foods as “good,” “bad” or “sinful” Environment Your environment can also play a major role in developing an eating disorder. These factors include: Family or other relationship problems Difficult or turbulent childhood History of physical or sexual abuse Activities that encourage thinness or focus on weight, such as gymnastics, dancing, running, wrestling and modelling Peer pressure Being bullied because of weight or appearance in general Watch: https://www.twig-world.com/film/malnutrition-1631/ https://www.twig-world.com/film/vitamin-deficiencies-1632/ https://www.twig-world.com/film/obesity-1650/ Read pages 134-136 from Grade 11 eBook and do Activity 9 28 Other problems associated with nutrition 29  Control of Sugar Grade 11 eBook pg 124 – 127 Watch: http://ed.ted.com/lessons/what-does-the-pancreas-do-emma-bryce https://www.twig-world.com/film/insulin-and-diabetes-1569/ Glucose is a simple sugar (monosaccharide). Glycogen is a complex carbohydrate and is the stored form of glucose. Glycogen is stored in the liver and muscles. Insulin and Glucagon are hormones produced from the pancreas which control the glucose level in the blood. Insulin helps to lower blood glucose levels by converting glucose into glycogen. Glucagon helps to increase blood glucose levels by converting glycogen back into glucose. The pancreas also produces enzymes which travel to the small intestine to allow for digestion of the macromolecules. 30  pancreas Glucagon causes Glycogen Pancreas stores in liver to be releases converted into Glucose Glucagon What is the role of the pancreas in blood sugar control? What is the role of the liver in blood sugar control? Do Grade 11 eBook page 126 & 127 Activity 4 31 32 Complete the worksheet on diabetes. 33  Organ Where found Structure & consists of Function - mechanical Function - chemical Mouth Oesophagus Stomach Small intestine Large intestine 34  Rectum Anus Liver Gall bladder Pancreas 35 Summary: Organic compounds Lipids Carbohydrates Proteins Elements Carbon Carbon Carbon Hydrogen Hydrogen Hydrogen Oxygen Oxygen Oxygen Nitrogen Monomers Fatty acids and Monosaccharides eg glucose, fructose, Amino acids eg glycine glycerol galactose Polymers Disaccharides: eg maltose, sucrose, Dipeptides lactose Polypeptides Polysaccharides: Plant starch is cellulose Proteins (more than 50 amino acids) Animal starch is glycogen (stored form of glucose) Functions 1 1 1 2 2 2 3 3 3 4 4 Extra information Amino acids join to form long chains called polypeptides fibrous proteins (long and thin eg for blood clotting) or globular proteins (blobs eg enzymes and hormones) – these shapes determine their functions 36 Extra information on proteins 2 important types of proteins are enzymes and hormones Hormones Enzymes – the names of most enzymes end in “ase” These are molecules (mainly protein) made in the endocrine These are molecules (globular proteins) made in exocrine glands (glands with glands (ductless glands). They travel in the blood stream to ducts) in different parts of the body. (eg the digestive glands found in the their target organs where they regulate activities. mucosa which produce the enzymes and the secretions which control pH etc)) They control all the chemical reactions in the body (metabolism) without Endocrine gland actually taking part in the reactions – they merely lower the energy required to Target force the molecules together to react – called activation energy. This reaction Bloodstream organ happens at the active site on the enzyme. Examples: Specific enzymes have specific jobs and their shapes are specific to their jobs. adrenalin – regulate various activities related to response to stress / fright They are very sensitive to pH and temperature and will only operate under oestrogen and progesterone – reproductive hormones specific conditions. If these conditions are changed their shape changes and thus Gastrin and secretin – help to regulate production of digestive the active site changes and thus it cannot work any longer. The conditions under enzymes which they operate the best are called optimum conditions. Insulin and glucagon – control blood sugar levels (produced in For most enzymes the optimal temperature is about 35 - 40 0 C (body the pancreas and work in the liver) temperature) and the optimal pH is about 7 BUT the digestive enzymes produced in the mouth, stomach, small intestine and pancreas each have their own optimal pH eg Mouth (alkaline) stomach (acid) small intestine (alkaline) 37