Download - Science Form 2 Nutrition notes

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Page 1: Science Form 2 Nutrition notes

2.1 Classes of Food

Classes Functions Examples

Carbohydrates

Supply main energy to body

sugars: cakes, cholates, fruits

starch: rice, bread, potatoes

cellulose: vegetables, fruit

glycogen (stored in the liver & muscle)

FatsSupply more energy & give heat to body

butter, cheese, margarine

ProteinsFor growth, repair and replace damaged cells

meat, fish, milk, eggs, beans,

  peas, nuts

Vitamins Maintain good health vegetables & fruits

MineralsFor proper growth & development of body

meat, milk, banana, seafood, eggs

Fibre To stimulate peristalsis fruits & vegetables

Water

Medium for chemical reaction in the body

waterRegulate 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 body

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CHAPTER 2: NUTRITION

Classes of Food

Carbohydrates

Fats

Proteins

Fibre

Minerals Vitamins

Water

Page 2: Science Form 2 Nutrition notes

Vitamins Functions Examples

Deficiency diseases

ATo promote healthy skins & eyes

carrot, tomatoes, green vegetables

Dry skin , night blindness

BMaintain healthy skin & nervous system

yeast, liver, vegetablesBeri-beri, Pellagra, Anaemia

C

To increase immunity against diseases

guavas, grapes, tomatoes,

Scurvy

Maintain healthy skin, teeth, gums

citrus fruit, vegetables  

D

Maintains healthy & strong teeth & bones

milk, eggs, fish

Rickets, softening of bones

Promotes calcium & phosphorus absorption

& teeth

EMaintain healthy reproduction system

seeds, nuts, egg yolk, whole grain

Sterility

K Blood clottingliver, egg yolk, green vegetables

prolong bleeding

Minerals Functions ExamplesDeficiency diseases

Sodium Maintain body fluid balancecheese, meat, table salt

muscle cramps

Potassium For nerve & muscle activities bananas, fish, meatparalysis, weak muscles

Calcium

Maintain strong & healthy teeth & bones

milk, eggs, anchovies,

Rickets, Osteoporosis,

Helps blood clotting green vegetables prolong bleeding

IronFormation of haemoglobin in red blood cell

liver, egg yolk, meat

Anaemia

IodineMake the hormones of the thyroid gland

seafood, seaweed Goitre

Phosphorus

Help in muscle contraction, make healthy cheese, milk, eggs

Rickets, tooth decay,

bones, and teeth weak muscle

Beri-beri (disease of nervous system)

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Page 3: Science Form 2 Nutrition notes

Pellagra (skin disease)

Anaemia (shortage of red blood cell)

Scurvy (bleeding gums)

Rickets (stunted growth) Goitre (swollen neck)

Kwashiorkor (lack of protein)

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Page 4: Science Form 2 Nutrition notes

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

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Food Test

Factors affecting balanced diet

Factors

Explanation Reason

Age

babies, children, & teenagers need more

Babies, children, and teenagers

energy than adults more active & life process faster

GenderMen need more energy than woman

Men are more active than woman

of the same age & body size  

Body size

Big size individuals need more energy Big size individual need more

than small size individual energy for life process

Health Patients’ needs more energy than Patients need more energy to conditio

nsomeone who is healthy recover from diseases.

Type of Heavy work need more energy Heavy work need more

job than light work energy to perform

ClimateIndividual live in cold weather need more

More energy required in cold weather

energy than individual live in warm to maintain body temperature

Classes

Type of test Reagent Result

Starch Iodin test Iodinebrown colour Iodine change into blue black

GlucoseBenedict's test / Fehling's test

Benedict's solution

brick-red precipitate formed

Proteins Millon's testMillon's reagent

white precipitate - red colour

Fats Emulsion testEtanol

milky solution or white emulsion formed

Filter paper

A translucent spot formed

Calorific value of food

Page 5: Science Form 2 Nutrition notes

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.

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Human digestive system

Page 6: Science Form 2 Nutrition notes

3. Chemical digestion – breaking down food by enzymes.

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

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Mouth Oesophagus Stomach Duodenum

Anus Rectum Large intestine Small intestine

Organs Functions

Mouth Cut & chews the food into smaller molecules

Oesophagus Channels food (bolus) to stomach through peristalsis action

Stomach Begins the digestion of protein

Duodenum Secret pancreatic juices to digest protein, carbohydrate, & fats

Small intestine Complete the food digestion and absorb end product of digestion

Large intestine Reabsorb water & minerals from indigested food

Rectum Store the faeces

Anus Removes faeces from body

Salivary glands Produce saliva which contain amylase enzyme

Liver Secrets bile to emulsify fats

Gall bladder Store bile which is secreted by liver

Pancreas Produce digestive enzymes (amylase, protease, lipase)

Organs Juices Enzyme Functions

Mouth Saliva (alkaline) Amylase Starch - Maltose

Stomach

Gastric juice Protease Protein - Polypeptide or Peptone

(acidic) Casein/Rennin Liquid milk protein - Solid form

Hydrochloric acid

Kills bacteria in the food

Duodenum

Pancreatic juice Amylase Starch - Maltose

(secreted by pancrease)

Protease Protein - Polypeptide or Peptone

(Alkaline) Lipase Fat - Fatty acid + Glycerol

Bile (alkaline greenish fluid secreted by liver)

Emulsify fats & oils into globules

Small intestine Intestinal juice

Maltase Maltose - Glucose

Protease Peptone - Amino acid

Lipase Fat - fatty acid + Glycerol

Page 7: Science Form 2 Nutrition notes

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.

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Food class End productCarbohydrate

Glucose

Protein Amino acid

Fat Glycerol + fatty acid

Absorption of digested food

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

Page 8: Science Form 2 Nutrition notes

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 diseases

4. 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.

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Reabsorption of water & defecation

Good eating habits

Page 9: Science Form 2 Nutrition notes

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 nutrition

8. 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.

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