Chapter 2: Nutrition Food can divided into seven classes as follows: Carbohydrates proteins fats vitamins minerals fibre water
CarbohydratePMR 03 FOOD TEST • Carbohydrate supplies us with energy to carry out daily activities such as walking, breathing, and working. made up of carbon, hydrogen and oxygen.
Protein PMR 04 made up of carbon, hydrogen, oxygen, and nitrogen • Proteins are required for building new cells for growth, to replace damaged tissue.
Fat made up for carbon, hydrogen and oxygenbut 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 • vitamins soluble in water – vitamin B and C , • vitamins soluble in fat- vitamin A, D, E and K.
Various types of vitamin • Vitamins are classified into two groups • vitamins soluble in water – vitamin B and C , • vitamins soluble in fat- vitamin A, D, E and K.
dieases pellagra anemia ricket Beriberi 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
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: • helping in the digestion of food • transporting digested food substances • transporting excretory products such as urea. • maintaining the concentration of blood. • maintaining the body temperature • 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
The calorific value of foodPMR 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.
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
Try to answer …. G A B H C I D J E K L 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. • The duodenum receives bile and pancreatic juice. (bile is 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. • The pancreatic amylasedigests starch into glucose • The protease digests protein/peptones into amino acids. • The lipase digests fat 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.
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 water-solube vitamins are absorbed into the blood capillaries.