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Chapter 2: Nutrition Food can divided into seven classes as follows: Carbohydrates proteins fats vitamins minerals fibre water Carbohydrate PMR 03 FOOD TEST made up of carbon, hydrogen and oxygen. •Carbohydrate supplies us with energy to carry out daily activities such as walking, breathing, and working. Protein PMR 04 made up of carbon, hydrogen, oxygen, and nitrogen •Proteins are required for building new cells for growth, to replace damaged tissue. Protein @ carbohydrate Fat made up for carbon, hydrogen and oxygen but the ratio is different from that of carbohydrate The function of fat include: a. supplying energy, b. as and insulator of heat to reduce heat loss from the body, c. protecting the internal organs such as the kidneys and the heart, dissolving some vitamins in the body like vitamin A, D, E and K. Vitamin Vitamins are classified into two groups 1.vitamins soluble in water – vitamin B and C , 2.vitamins soluble in fat- vitamin A, D, E and K. Vitamin A B Various types of vitamin Main source Egg, milk, cod liver, oil, carrot, papaya yeast, egg, milk, tomato, liver, nuts - - - C D E K lime, citrus fruits, tomato, carrot , papaya, green vegetables egg, milk, cod liver oil vegetable oil, palm oil, egg, liver, milk maize, sunflower seeds, tomato, green vegetables - Function for growth and to promote healthy skin for good vision promotes the effective functioning of the nervous system control the supply of carbohydrates to the muscle and nerve cells increase immunity against disease promotes healthy skin - helps in the absorption of calcium and phosphorus in the small intestines for the growth of strong bones and teeth. - maintains a healthy reproductive system - necessary for the clotting of blood. •Vitamins are classified into two groups 1.vitamins soluble in water – vitamin B and C , 2.vitamins soluble in fat- vitamin A, D, E and K. Effect of deficiency night blindness dry and scaly skin - - beri-beri (injury to the nervous system and paralysis) pellagra anaemia scurvy (gusi merah) anaemia low resistance to infections (especially the flu) - rickets (weak and curved bones) - tooth decay - sterility - infertility - blood slow to clot PMR 2011 dieases pellagra anemia ricket Beri beri scurvy Minerals •minerals are simple chemicals usually found in the body. •our bodies need more calcium and phosphorus than the minerals. •(because they help to form strong bones and teeth) •minerals are needed for good health. Sources and functions of minerals as well as the effects of mineral deficiencies effects of deficiency * rickets * brittle bones and teeth * poor blood clotting Minerals sources of food Functions Calcium milk, eggs, vegetables, cheese * forms strong bones and teeth * helps blood to colt iron liver,, meat, eggs, vegetables iodine seafood, vegetables, iodinised salt * forms haemoglobin in red the thyroid blood cells * produces hormones in the thyroid gland sodium common salt, * balances body fluid phosphorus meat, milk, eggs, beans * forms strong bones and teeth * muscle cramps * rickets * dental decay fluorine drinking water, fish, vegetables * protect teeth * Dental decay potassium meat, fish, cereals * maintains a healthy nervous system * muscle cramps * anaemia * Goitre Fibre •Fibre is made up of cellulose which cannot be digested by the body. •A shortage of fibre in our daily diet can cause constipation and sometimes even bowel cancer. •Vegetables, fruit, beans, lentils and brown bread are examples of food rich in fibre. Water Water is needed by the body for: 1. helping in the digestion of food 2. transporting digested food substances 3. transporting excretory products such as urea. 4. maintaining the concentration of blood. 5. maintaining the body temperature 6. all metabolic processes The importance of a balanced diet • A balanced diet is one which contains carbohydrates, proteins, fats, minerals, vitamins, water and fibre in the correct quantities and proportions. • A balanced diet is necessary for: – – – – supplying the required energy balanced body growth maintaining the health of the body preventing deficiency diseases such as scurvy and rickets. • A balanced diet varies according to one’s – – – – – – Age size sex job climate state of health Factors that influence a person’s needs for a balanced diet Factors sex age body size physical activity weather the group requiring more energy men required more energy compared to women of the same age and body size. babies, children and teenagers require more energy compared to adults or the elderly. Example: the heartbeat of baby is 100 beats a minute compared to an adult who has 75 beats per minute. big-size individuals require more energy size compared to small-sized individuals. Reason men are more active this group is more active and the life processes are faster. big-sized individuals require more energy for their life processes. an individual who does heavy work uses heavy work requires more more energy compared to another who energy to perform. does light work. more energy is required to individuals living in places with cold maintain the body temperature weather require more energy compared in a cold place. to individuals living in places with warm weather. The calorific value of food PMR 06, 07, 11 • The calorific value of food is the amount of heat energy released when one gram of food is completely burnt in the air. • The calorific value of food is measured in kilojoules per gram (kJ/g) or kilocalories per gram (kcal/g) • The calorific value differs for different types of food. Table below shows the calorific value of some of the food that we eat daily. The calorific value of food PMR 06, 07, 11 Kedah 12 FOOD TEST (experiment) PMR 03 Classes of food Tester observation Glucose Benedict solution Fehling Solution Brick-red precipitate Heat Protein Millon reagent Brick-red precipitate Heat Starch Iodine solution Dark blue No need to heat Fat - Filter paper - Alcohol/ethanol -Translucent spot - white-emulsion (cloudy) - Heat - No need to heat Food test PMR 2011 Kedah 2012 HUMAN DIGESTIVE SYSTEM • Digestion is the process of breaking down large and complex food substances into smaller, simpler molecules. These molecules are soluble and can be absorbed by body cells. • The process of digestion in the alimentary canal: a. physical digestion /mechanical digestion – involves the mechanical process of breaking down large pieces of food into smaller particles using the teeth and the churning movements of the alimentary canal. • b. - chemical digestion involves the action of various enzymes in breaking down complex food molecules. These complex molecules are insoluble but the end products of chemicals digestion are simpler molecules which are soluble. Human Digestive system mouth anus The liver also plays a vital role in excretion. It removes toxic chemicals from the blood through a series of chemical reactions. trakea perut pancreas Usus kecil Usus besar Human digestive system…. Try to answer …. G A B H I J K L C D E F Mouth • i. Digestion begins in the mouth. • ii. The teeth chew and grind food into smaller particles. • the salivary glands secrete glands secrete saliva which contains an enzyme called amylase. • Amylase digests starch and converts it to maltose, a type of sugar. • The wave-like contractions of the oesophagus muscles are known as peristalsis. stomach • in the stomach, food is mixed with gastric juices. Gastric • glands in the stomach wall. – Gastric juices contains hydrochloric acid and enzymes (rennin and pepsin) . – rennin – coagulate milk. – Pepsin – digest protein into peptone (amino acid) – The functions of hydrochloric acid include: • Hydrochloric acid stops the action of the enzymes in saliva. • It also kills bacteria in food. – Enzymes in the gastric juices start the digestion of protein. Example: • – Partially digested food is then released into the duodenum. small intestine • The duodenum is the first parts of the small intestine. bile and pancreatic juice. (bile is – The duodenum receives stored in the gall bladder) – The function of bile: • Emulsifications of fat i.e. breaking up large fatty globules into small droplets for enzymic action. • Preparation of an alkaline medium for enzymic action. starch into glucose – The protease digests protein/peptones into amino acids. – The pancreatic amylase digests fat – The lipase digests into fatty acid and glycerol. – The small intestine (ileum) produces enzymes which digest maltose into glucose (simple sugar) – Digestion is completed in the small intestine. – The digested food is then ready to be absorbed through the thin walls of the small intestine into the bloodstream. PMR 2004 PMR 2005 Selangor 2011 PMR 2011 Absorption of digested food • The efficiency of absorption of digested food at the small intestine can be increased by: • more villus to increase surface area • villus with very thin walls • Each villus has a network of a blood capillaries and a lacteal. • Glucose, amino acids, minerals and water-solube vitamins are absorbed into the blood capillaries. • Fatty acids, glycerol and fat-soluble vitamins (vitamin A, D, E and K) are absorbed into the lacteal. Lacteal and blood capillary in villus • The efficiency of absorption of digested food at the small intestine can be increased by: – more villus to increase surface area • • • • villus with very thin walls • • • • Large of surface area (more villi) Thin wall (one cell thick) Moist surface (enable gas to dissolve) Surrounded by a network of blood capillaries. Each villus has a network of a blood capillaries and a lacteal. Glucose, amino acids, minerals and water-solube vitamins are absorbed into the blood capillaries. Fatty acids, glycerol and fat-soluble vitamins (vitamin A, D, E and K) are absorbed into the lacteal. • Fatty acids, glycerol and fat-soluble vitamins (vitamin A, D, E and K) are absorbed into the lacteal. • Glucose, amino acids, minerals and watersolube vitamins are absorbed into the blood capillaries. Resap - difuse End product of digestion Class of food Carbohydrate s/starch Protein Fat enzyme Amylase End product Glucose Protease lipase Amino acid Fatty acid & glycerol Parts of the digestive tract parts of the digestive tract Mouth Oesophagus Stomach PMR 03 Duodenum small intestine large intestine Rectum Anus Functions chew and grinds food using the teeth digests cooked starch. The amylase enzymes in the saliva change cooked starch to maltose. The salivary glands secrete saliva which contains an enzyme called amylase. Amylase digests starch and convert it to maltose (a type of sugar) bolus-shaped food is moved from the mouth to the stomach along the oesophagus by wave-like muscular contractions called peristalsis. holds food, secretes gastric juices which begin the digestion of protein secretes acids contains hydrochloric acid which kill the bacteria in food. receives bile from the liver and pancreatic juice from the pancreas. Digestion and absorption of food. secretes intestinal juice which completes the digestion of protein, carbohydrates and fat. Absorbs end products of digestion into the blood. absorption of most of the remaining water and minerals. stores faeces removes faeces through defecation. Chemical digestion in human digestive Part Mouth Secretes Source of secretes End product Saliva Salivary gland Starch maltose/glucose Hydrochloric acid Wall of the stomach Destroy bacteria in food. Prepare acid medium for digestion in stomach. Stomach Gasteric juice/jus gaster Duodenum Bile Liver Emulsify of fat. Prepare alkali medium for digestion in small intestine. Pancreatic juice Pancreas Starch maltose/glucose Protein peptone/amino acid Fat fatty acid & glycerol Wall of the small intestine Maltose glucose Peptone amino acid Small intestine Protein peptone R&R PART OF ALLIMANTARY CANAL SECRETED BY Characteristic of secretion MOUTH SALIVA Alkaline STOMACH GASTER JUICE Acidic BILE Alkaline PANCREAS JUICE DUODENUM CARBOHYDRATE Alkaline PROTEIN SMALL INTESTINE INTESTINE JUICE CLASS OF FOOD INVOLVE REACTION AND DIGESTION PRODUCT CARBOHYDRATE STARCH MALTOSE PROTEIN PEPTONE PROTEIN FAT FAT DROPS OF FAT FAT DROPS OF FAT FATTY ACID + GLYCEROL STARCH STARCH MALTOSE PEPTONE PEPTONE AMINO ACID PROTEIN PEPTONE AMINO ACID CARBOHYDRATE COMPLEX SUGAR alkaline SIMPLE SUGAR Digestion, absorption and use of food in human beings nutrients carbohydrates proteins fats Digestion Amylase (mouth, small intestine) Protease (stomach, small intestine) Lipase (small intestine) End products glucose Amino acids Fatty acids and glycerol diffuse in small intestine HEALTHY EATING HABITS The food pyramid PMR 05, 08 Food Pyramid Absorption of the products of digestion • The inner surface of the small intestine (6 metres long) covered with millions of small projections about 1mm long. These projections are called villi @ villus. villi • The efficiency of absorption of digested food at the small intestine can be increased by: • more villus to increase surface area • villus with very thin walls Visking tube (experiment) • Visking tube • Water temperature • water REABSORPTION OF WATER AND DEFACATION • Reabsorption of water • The main function of big intestine is to reabsorb water. • Defecation • Undigested food in the big intestine is expelled as faeces through the process of defecation. Healthy eating habits • Healthy eating habits will help maintain a healthy body. • Unhealthy eating habits cause various health problems. 1. excessive nutrient Sugar Salt fat/oil 2. lack of nutrient Protein Roughage/fiber Vitamins health problems tooth decay, obesity, diabetes high blood pressure, heart problems, kidney damage heart problems, high blood pressure health problems kwashiorkor in children Constipation lower immunity to diseases Penutup 1. Baca Surah Al-`Ashr 2. Tasbih Kifarah.