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.

c.

as and insulator of heat to reduce heat loss from the body, 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 C D E K

Various types of vitamin

Main source Egg, milk, cod liver, oil, carrot, papaya yeast, egg, milk, tomato, liver, nuts 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 a nd phosphorus in the small intestines for the growth of strong bones and teeth.

- maintains a healthy reproductive system - necessary for the clotting of blood.

-

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

•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.

PMR 2011

ricket Beri beri pellagra

dieases

anemia 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 Minerals Calcium sources of food milk, eggs, vegetables, cheese Functions * forms strong bones and teeth * helps blood to colt effects of deficiency * rickets * brittle bones and teeth * poor blood clotting iron iodine liver,, meat, eggs, vegetables seafood, vegetables, iodinised salt * forms haemoglobin in red the thyroid blood cells * produces hormones in the thyroid gland * anaemia * Goitre sodium phosphorus common salt, meat, milk, eggs, beans * balances body fluid * 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

Fibre

•Fibre is made up of cellulose which cannot be digested by the body.

•A shortage of fibre in our daily diet can cause c onstipation and sometimes even •Vegetables, fruit, beans, lentils and brown bread are examples of food rich in fibre.

bowel cancer .

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 the group requiring more energy men required more energy to women of the same age and body size.

compared 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 energy size compared to small-sized individuals.

individuals require more an individual who does heavy work uses more energy compared to another who does light work.

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.

heavy work requires more energy to perform.

weather individuals living in places with cold weather require more energy compared to individuals living in places with warm weather.

more energy is required to maintain the body temperature in a cold place.

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

Glucose Protein Starch Fat

Tester

Benedict solution Fehling Solution Millon reagent Iodine solution - Filter paper - Alcohol/ethanol

observation

Brick-red precipitate Heat Brick-red precipitate Dark blue -Translucent spot - white-emulsion (cloudy) Heat No need to heat - 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….

L H I J K

Try to answer ….

G A E C D F B

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 amylase digests

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.

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 capilla ries.

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 .

Resap - difuse

End product of digestion

Class of food

Carbohydrate s/starch Protein Fat

enzyme

Amylase Protease lipase

End product

Glucose Amino acid Fatty acid & glycerol

parts of the digestive tract Mouth Oesophagus Stomach PMR 03 Duodenum small intestine large intestine Rectum Anus               Parts of the digestive tract 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 sugar)

maltose

(a type of 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 Stomach Duodenum Small intestine

Secretes

Saliva Hydrochloric acid Gasteric juice/jus gaster Bile Pancreatic juice

Source of secretes

Salivary gland Wall of the stomach Liver Pancreas Wall of the small intestine

End product

Starch  maltose/glucose Destroy bacteria in food.

Prepare acid medium for digestion in stomach.

Protein  peptone Emulsify of fat.

Prepare alkali medium for digestion in small intestine.

Starch  maltose/glucose Protein  Fat  peptone/amino acid fatty acid & glycerol Maltose  Peptone  glucose amino acid

R & R

PART OF ALLIMANTARY CANAL MOUTH STOMACH DUODENUM SECRETED BY SALIVA GASTER JUICE BILE PANCREAS JUICE CARBOHYDRATE PROTEIN Characteristic of secretion Alkaline Acidic Alkaline Alkaline SMALL INTESTINE INTESTINE JUICE alkaline CLASS OF FOOD INVOLVE CARBOHYDRATE PROTEIN FAT FAT STARCH PEPTONE PROTEIN CARBOHYDRATE REACTION AND DIGESTION PRODUCT STARCH MALTOSE PROTEIN PEPTONE FAT DROPS OF FAT DROPS OF FAT FATTY ACID + GLYCEROL STARCH MALTOSE PEPTONE AMINO ACID PEPTONE AMINO ACID COMPLEX SUGAR SIMPLE SUGAR

Digestion, absorption and use of food in human beings nutrients carbohydrates proteins fats Digestion End products Amylase (mouth, small intestine) glucose Protease (stomach, small intestine) Amino acids Lipase (small intestine) 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 health problems tooth decay, obesity, diabetes high blood pressure, heart problems, kidney damage fat/oil 2. lack of nutrient Protein Roughage/fiber Vitamins heart problems, high blood pressure health problems kwashiorkor in children Constipation lower immunity to diseases

1. Baca Surah Al-`Ashr

Penutup

2. Tasbih Kifarah.