2.1Classes of Food

ClassesFunctionsExamples

CarbohydratesSupply main energy to bodysugars: cakes, cholates, fruits

starch: rice, bread, potatoes

cellulose: vegetables, fruit

glycogen (stored in the liver & muscle)

FatsSupply more energy & give heat to bodybutter, cheese, margarine

ProteinsFor growth, repair and replace damaged cellsmeat, fish, milk, eggs, beans,

peas, nuts

VitaminsMaintain good healthvegetables & fruits

MineralsFor proper growth & development of bodymeat, milk, banana, seafood, eggs

FibreTo stimulate peristalsisfruits & vegetables

WaterMedium for chemical reaction in the bodywater

Regulate body temperature

Transport digested food & waste materials

Excess carbohydrates stored as fat in the body.

Vitamins A, D, E, K fats soluble

Vitamins B, C Water soluble Vitamins required in small quantity for bodyVitaminsFunctionsExamplesDeficiency diseases

ATo promote healthy skins & eyescarrot, tomatoes, green vegetablesDry skin , night blindness

BMaintain healthy skin & nervous systemyeast, liver, vegetablesBeri-beri, Pellagra, Anaemia

CTo increase immunity against diseasesguavas, grapes, tomatoes,Scurvy

Maintain healthy skin, teeth, gumscitrus fruit, vegetables

DMaintains healthy & strong teeth & bonesmilk, eggs, fishRickets, softening of bones

Promotes calcium & phosphorus absorption& teeth

EMaintain healthy reproduction systemseeds, nuts, egg yolk, whole grainSterility

KBlood clottingliver, egg yolk, green vegetablesprolong bleeding

MineralsFunctionsExamplesDeficiency diseases

SodiumMaintain body fluid balancecheese, meat, table saltmuscle cramps

PotassiumFor nerve & muscle activitiesbananas, fish, meatparalysis, weak muscles

CalciumMaintain strong & healthy teeth & bonesmilk, eggs, anchovies, Rickets, Osteoporosis,

Helps blood clottinggreen vegetablesprolong bleeding

IronFormation of haemoglobin in red blood cellliver, egg yolk, meatAnaemia

IodineMake the hormones of the thyroid glandseafood, seaweedGoitre

PhosphorusHelp in muscle contraction, make healthy cheese, milk, eggsRickets, tooth decay,

bones, and teethweak muscle

Beri-beri (disease of nervous system)Pellagra (skin disease)

Anaemia (shortage of red blood cell)Scurvy (bleeding gums) Rickets (stunted growth)

Goitre (swollen neck) Kwashiorkor (lack of protein)

Balanced diet Diet which contains all seven types of food classes in the right quantities & proportions.

1. Digestion process of breaking down large food molecules into smaller molecules that can be absorbed by body.2. Physical digestion breaking down food into smaller particles by teeth.3. Chemical digestion breaking down food by enzymes.

4. Peristalsis Contraction & relaxation of digestive tract to channel the food throughout the digestive tract.

1. Absorption of end product take place in small intestine through the diffusion process.2. Length of small intestine 6 metre. Walls of small intestine is folded to increase its surface area.

3. Features of small intestine:

a. Have many finger-like projections known as villi (singular: villus).b. Have many blood capillaries to facilitate absorption.c. Very long about 6 m allows greater absorption.

d. Very thin so that small molecules can enter the blood capillaries.e. Moist lining enables food molecules to dissolve easily.4. Vilus or Villli the surface of small intestine covered with millions of tiny finger-like projections.

5. Functions of vilus Absorb digestion food effectively.

1. Undigested food enters the large intestine.

2. Reabsorption of water & minerals from undigested food (e.g cellulose, fibre) take place. 3. Defecation process where faeces removed from body.4. Faeces is formed and stored in the rectum. Then, removed through anus.

1. Good eating habits Eating nutritious food in right quantities & proportion.2. Healthy eating habits:

a. Eat plenty of vegetables & fruit.

b. Consume less sugar & salt

c. Eat in moderation

d. Drink plenty of water

e. Chew food thoroughly before swallowing

f. Eat nutritious food

g. Avoid junk food

3. Unhealthy eating habits:

a. Consume high sugar lead to diabetes

b. Consume high salt lead to blood pressure

c. Consume too much fat lead to high blood cholesterol and heart diseases4. Constipation difficulty to defecate hard faeces from body.5. Causes of constipation lack of water & roughage in diet. To avoid constipation, must eat food such as fruits, vegetables, and grains.

6. Over weight/ Obesity Excess body fat which can cause health problem such as diabetes, hypertension, heart diseases, cancer, & failure in respiratory and excretory systems.7. Causes of obesity Genetic, lack of exercise, unbalanced nutrition8. Saturated fat is bad for body because fat will accumulate in the blood stream and cause blockage of blood vessels and lead to heart attack and stroke.CHAPTER 2: NUTRITION

Classes of Food

Carbohydrates

Fats

Proteins

Fibre

Minerals

Vitamins

Water

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Food Test

ClassesType of testReagentResultStarchIodin testIodinebrown colour Iodine change into blue blackGlucoseBenedict's test / Fehling's testBenedict's solutionbrick-red precipitate formedProteinsMillon's testMillon's reagentwhite precipitate - red colourFatsEmulsion testEtanolmilky solution or white emulsion formedFilter paperA translucent spot formed

Factors affecting balanced diet

FactorsExplanationReasonAgebabies, children, & teenagers need more Babies, children, and teenagers energy than adultsmore active & life process fasterGenderMen need more energy than woman Men are more active than womanof the same age & body sizeBody sizeBig size individuals need more energy Big size individual need morethan small size individual energy for life processHealthPatients needs more energy than Patients need more energy to conditionsomeone who is healthyrecover from diseases.Type ofHeavy work need more energy Heavy work need more jobthan light workenergy to performClimateIndividual live in cold weather need more More energy required in cold weatherenergy than individual live in warm weatherto maintain body temperature

Calorific value of food

Human digestive system

Mouth

Oesophagus

Stomach

Duodenum

Anus

Rectum

Large intestine

Small intestine

OrgansFunctionsMouth Cut & chews the food into smaller moleculesOesophagus Channels food (bolus) to stomach through peristalsis actionStomach Begins the digestion of proteinDuodenum Secret pancreatic juices to digest protein, carbohydrate, & fatsSmall intestine Complete the food digestion and absorb end product of digestionLarge intestine Reabsorb water & minerals from indigested foodRectum Store the faecesAnus Removes faeces from bodySalivary glands Produce saliva which contain amylase enzymeLiver Secrets bile to emulsify fatsGall bladder Store bile which is secreted by liverPancreas Produce digestive enzymes (amylase, protease, lipase)

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OrgansJuicesEnzymeFunctionsMouthSaliva (alkaline)AmylaseStarch - MaltoseStomachGastric juiceProteaseProtein - Polypeptide or Peptone(acidic)Casein/RenninLiquid milk protein - Solid formHydrochloric acidKills bacteria in the foodDuodenumPancreatic juiceAmylaseStarch - Maltose(secreted by pancrease)ProteaseProtein - Polypeptide or Peptone(Alkaline)LipaseFat - Fatty acid + GlycerolBile (alkaline greenish fluid secreted by liver)Emulsify fats & oils into globulesSmall intestine

Intestinal juiceMaltaseMaltose - GlucoseProteasePeptone - Amino acidLipaseFat - fatty acid + Glycerol

Water, minerals, vitamins are need not to be digested because these food are very small and simple molecules that can be absorbed into body.

Food classEnd productCarbohydrateGlucoseProteinAmino acidFatGlycerol + fatty acid

Absorption of digested food

Reabsorption of water & defecation

Good eating habits

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