a. Solvent for many substances in the bodyb.Regulate body temperature
1. A balanced diet contains the right amount of the seven classes of food to meet the daily requirements of the body.2. Abalanced diet is necessary for: a. supplying the required energy b. balanced body growth c. maintaining the health of the body d. preventing deficiency diseases such as scurvy and rickets
FACTOR THEGROUP REASON REQUIRINGMORE ENERGYA.Sex Menrequiring Menaremore moreenergyof active thesameage andbodysizeB.Age Babies,children Thisgroupis andteenagers moreactiveand requiremore thelifeprocess energy arefaster
1. The calorific value of food is the total energy produced when one gram of food is completely burnt.2. The quantity of energy in a food is measured in calorie (cal) or joule (j)3. 1 calorie (cal) = 4.2 joule (j) 1 kilocalorie (kcal) = 4.2 kilojoules (kJ)
Digestion1. Digestion is the process of breaking down complex food to simple molecules for absorption the blood circulatory system.2. Digestion take place in two stages: a. physical digestion – big pieces of food are broken down into smaller pieces by teeth b. chemical digestion – enzymes break up complex food molecules into smaller molecules
3. Enzymes are proteins that speed up the process of digestion. Enzymes break up complex food molecules to smaller and simpler molecules.4. Characteristic of enzymes a. enzymes are small quantities only b. enzymes are not destroyed at the end of digestion c. specific enzymes act only in specific acidic or alkaline conditions d. specific enzymes act only on specific foods e. enzymes function best at normal body temperature (370 C) Enzymes are destroyed at high temperature.
1. The digestive system consists of all the organ in the body that help in the digestion of food.2. The alimentary canal is made up of the mouth, oesophagus, stomach, small intestine, big intestine and anus (starts from the mouth and ends at the anus).
3. Summary of the digestive system mouth oesophagus stomach small intestine big intestine anus4. Food is pushed along the alimentary canal by the muscular walls that contract and expand alternately through the process of peristalsis.
Mouth Oesophagus StomachDuodenum Lower part of small intestine Appendix
1. Food is chewed and broken up into small pieces by the teeth.2. Small pieces of food have a wide surface area for the saliva to act upon.3. The salivary gland secretes saliva that is alkaline and contains salivary amylase enzymes.4. Salivary amylase digests starch into maltose (sugar) amylase starch maltose
1. Food is pushed through the oesophagus into the stomach by the alternating r contraction and relaxation of the oesophagus.2. This process of alternating muscular contraction and relaxation is known as peristalsis.
1. Food is mixed with gastric juice in the stomach.2. Gastric juice is secreted from the cells of the stomach wall. Gastric juice contains: a. hydrochloric acid b. enzymes (rennin and pepsin)3. The function of hydrochloric acid include a. providing an acidic medium for enzymic action. b. killing bacteria found in food c. neutralising the alkaline property of saliva
4. Pepsin digest protien to peptones / polypeptides Protien pepsin peptones/ polypeptides5. Rennin coagulates milk in the stomach to help in the enzymic enzymes. rennin Liquid milk protiens solid milk protiens
1. The duodenum is the first part of the small intestine.2. The duodenum received bile and pancreatic juice.3. The function of bile are: a. emulsification of fat b. preparation of an alkaline medium for enzymic action4. Pancreatic juice contains three types of enzymes: a. maltase b. protease c. lipase
5. The maltase digests maltose into glucose maltase maltose glucose6. The protease digests peptones into amino acids protease peptones amino acids7. The lipase digests fat into fatty acid and glycerol lipase fat fatty acids + glycerol
8. Digestion is completed in small intestine.9. The digest food is then ready to be absorbed through the thin walls of the small intestine into the bloodstream.10. Food digestion is completed in the small intestine.11. The end products of digestion are a. Carbohydrate - glucose b. Protien - amino acids c. Fats - fatty acids and glycerol .
1. Water is reabsorbed in the big intestine2. Undigested food is expelled from the body through the anus as faeces.
1. The inner surface of the small intestine has many villi.2. The villi increase the surface area for the absorption of digested food.3. Absorption is the movement of digested food into the bloodstream
Reabsorption of Water and Defecation Residue from the small intestine Reabsorption of water + minerals + vitamins Solid waste called faeces Stored in the last part of the large intestine Defecation through the anus
Difficulty in defecation is calledconstipation. Prolonged and serious constipation can lead to ….. • Hemorrhoids (piles) • Cancer of the large intestine Defecation is removal of faeces from the body through the anus
Why causes constipation?Not eating enough roughage Not drinking enough water Cause Constipation
1. Therefore, constipation can be cured by • taking laxatives • eating high fibre foods such as wholemeal cereals and grains, fruits and vegetables • taking more fluidRemember, prevention is always better than curing
HEALTY EATING HABITS.Unhealthy eating habits is the main cause of many diseases• Too much sugar diabetes• Too much salt high blood pressure• Too much fat obesity, high blood cholesterol level, cancers• Too much food obesity• Too little food anorexia nervosa, bulimia• Too little roughage constipation, haemorroids
So, cultivate healthy eating habits to stay healthy• Eat a variety food according to the recommended amountshown in a food guide pyramid. Eat least Eat most
• Eat in moderation. Balance food intake with exercise• Choose nutritious food Nutritious food Less nutritious food • Fresh fruits • Junk food • Fresh vegetables • Highly processed food • Wholemeal cereal, grains or • Fast foods bread • Fizzy drinks • Unpolished rice
• Read food labels• Do not be misled by food advertisements• Eat at regular time
Summary Chart Nutrition Food Healthy eating habits Classes, Food tests Calorific valuesources and functions Balanced diet Digestion Absorption of Absorption of digested food water and Defecation dissolved minerals