Nutrition f1 igcse

FORM 2: CHAPTER 2 NUTRITION

CHAPTER 2CHAPTER 2

NUTRITIONNUTRITION


CLASSES OF FOOD

CARBOHYDRATE PROTEINS FATS VITAMINS MINERALS WATER FIBRE


CARBOHYDRATE Organic compound: carbon, hydrogen, oxygen Include sugars (sweet foods), starch (starchy

foods) and cellulose (plant cell wall) Functions of carbohydrate:

To supply energy As stored food:

*excess glucose glycogen starch

In animals

In plants

(stored in liver and muscle)


Test for starch and glucose


PROTEINS Organic compound: carbon , hydrogen,

oxygen & nitrogen Made up of large number of subunits called

amino acids Not all amino acids can be made by our body

cells Source:

Meat, fish, egg, dairy products (animal protein) Soy bean, legumes (plant protein)

(sometimes sulphur & phosphorus)


PROTEINS (CONT)

Functions: Growth and repair of the body tissue Formation of enzymes, hormones, heamoglobin and

antibodies (protein compounds) Provide energy (proteins can be broken down into

glycogen during lack of carbohydrate & fat)


Test for proteins


FATS Organic compound: carbon, hydrogen, oxygen Combination of fatty acids and glycerol Stored under skin or around organs in the body Fats are solid in room temperature, oil is liquid

in room temperature Sources: butter, cheese, margarine, palm oil,

ghee.


FATS FATS (CONT)(CONT)

Functions: Keep us warm (heat insulator) Protect organs from damage Transport vitamins (A, D, E, K) Store lots of energy


Test for fats


VITAMINSVITAMINS

Organic compound Needed small amount for our body Have two types:

Water soluble: vitamins B and C Fat soluble: vitamins A, D, E, K


Source: milk, carrot, cod liver oil, eggs

Important for good vision

Deficiency can cause night blindness, dry and scaly skin


Important for healthy skin and good nerve function

Deficiency can cause beri-beri (damage of nervous system) and pellagra (skin disease)


Beri-beri diseaseBeri-beri disease


Important for : healthy gums and

skin prevents infections

Deficiency can cause: scurvy Easy to get coughs

and flu


Scurvy diseaseScurvy disease


Important for strong bones and healthy teeth

•Deficiency can cause rickets (dental decay and weak bones)


Rickets disease Rickets disease


Important for healthy reproductive system

Deficiency can cause Sterility poor muscle and

nerve functions


Important for blood clotting

Deficiency can slow clotting of blood



MINERALSMINERALS

Inorganic substances Needed in small amount in our body Excess minerals are removed from the body

through sweat and urine


Functions: Formation of

strong bones Blood clotting Good muscle

and nerve function

Deficiency diseases:- Rickets - Prolonged bleeding

- Osteoporosis - Muscular cramp


SODIUMSODIUM

Deficiency disease: Muscle cramps

Functions: Important component of

body fluid Proper nerve function


IRONIRON

Deficiency disease: Anaemia

Functions: Formation of

haemoglobin


IODINEIODINE

Deficiency disease: Goitre (swelling

of thyroid glands)

Functions: Needed to

make hormones of thyroid glands


PHOSPHORUSPHOSPHORUS

Deficiency disease: Rickets and weak

bones

Functions: Formations of strong

bones


POTASSIUMPOTASSIUM

Deficiency disease: Muscle tiredness paralysis

Functions: Healthy nervous system



WATERWATER

70% of body weight Main component of blood and body fluid Dissolve lots of chemicals in our body and

allows the chemical to react To eliminate waste substances To regulate body temperature


FIBREFIBRE

Known as roughage Made of cellulose from plant cell wall Source: Fruits, vegetables and cereal Fibre cannot be digested by human Fibre can hold lots of water, prevent

constipation


THE IMPORTANCE OF A THE IMPORTANCE OF A BALANCED DIETBALANCED DIET

All food we eat everyday is known as diet. A balanced diet is a diet that contains all classes

of food in the right quantity and ratio according to our body needs.

Each person needs different amount of food.




7 factors that affect a balanced diet:1. Body size2. Age3. Gender4. Occupation5. Physical activity6. Climate 7. Health


GROUP AGE SEX BODY ACTIVITY

ENERGY REQUIREMENTS (Kj)

CHILD5 FEMALE MODERATE 6 800

5 MALE MODERATE 7 600

ADOLESCENT14 FEMALE MODERATE 9 200


ADULT

25 FEMALE MODERATE 8 500

25 MALE ACTIVE 10 500


25 MALE ACTIVE 14 000




A balanced diet is important to: Ensure body growth Maintain optimum body health Repair and replace old or damage tissues Ensure enough energy for the body according its

needs

Diet imbalance in the long run causes a person to contract deficiency diseases or is known as malnutrition


CALORIFIC VALUE OF FOODSCALORIFIC VALUE OF FOODS

The energy that is stored in food is referred to as The energy that is stored in food is referred to as calorific value or energy value of foodcalorific value or energy value of food

TheThe calorific value of foodcalorific value of food is defined as theis defined as the amount of energy released from 1 gram of a amount of energy released from 1 gram of a particular type of food.particular type of food.

The calorific value of food is measured inThe calorific value of food is measured in calories calories (cal) or joules (J)(cal) or joules (J)

1 calorie = 4.2 joules1 calorie = 4.2 joules 1000 calories (cal) = 1 kilocalorie (kcal)1000 calories (cal) = 1 kilocalorie (kcal) 1000 joules (J) = 1 kilojoules (kJ)1000 joules (J) = 1 kilojoules (kJ)


How to calculate the calorific value of food?

Example:

The calorific value of 100 g of fried noodles is 595 kJ. Asmah eat 250 g of fried noodle as her breakfast. So, the calorific value of the food that she eat is:

100 g = 595 kJ

250 g = ?????1487.5 kJ


Estimate the calorific value for the following meals

MEAL 1

1 plate of nasi lemak

2 pieces of doughnut

1 cup of coffee

MEAL 2

1 piece of egg banjo

1 glass of chocolate milk

2558 kJ

2367 kJ


HUMAN DIGESTIVE SYSTEMHUMAN DIGESTIVE SYSTEM

MOUTHMOUTH





Premolar

Premolar








THE MAIN FUNCTION MOUTH: Keeps the food for chewing TEETH: Cut the food into small pieces SALIVARY GLANDS: Produce saliva containing

digestive enzyme (amylase) TONGUE: Tastes the food OESOPHAGUS: Channels the food from the mouth

into the stomach STOMACH: Produces digestive enzymes to digest the

food DUODENUM: Digests the food with the help of

enzymes from the pancreas


PANCREAS: Produces digestive enzymes (amylase, protease and lipase)

LIVER: Produces bile for emulsifying fats GALL BLADDER: Stores bile from the liver SMALL INTESTINE: Produce digestive

enzymes and completes the digestion of food LARGE INTESTINE: Absorbs water from

the undigested food RECTUM: Keeps the faeces ANUS: Lets out the faeces


The digestive system consists of all the organs which take part in the digestion of food.

The alimentary canal consists of the parts through which food passes from the mouth to the anus.

Food passes through the alimentary canal along the following pathway:

Mouth → oesophagus → stomach → duodenum → small intestine → large intestine →anus


THE DIGESTION OF FOOD

Process of changing the food eaten from large complex molecules to small simple molecules which can pass through the cell membranes into the cells of the body.

The physical digestion (process) : Food is broken into small pieces (chewing by teeth, churning of food in stomach)

The chemical process: Large complex of food molecules are changed into small and simple molecules which can be absorbed by the body (action of enzymes on food)


MOUTH


MOUTH

The food in the mouth is first cut into small pieces by the teeth and mixed with the saliva

The small pieces of food provide a larger surface area for the amylase enzyme in the saliva to act on the starch.

The amylase changes the cooked starch into maltose.


OESOPHAGUS


OESOPHAGUS

The partly digested food is swallowed into the oesophagus.

Peristalsis of the wall of the oesophagus (contraction and relaxation of the muscular wall) pushes the food down the oesophagus into the stomach.

Food is push downwards


STOMACH


STOMACH

The food is mixed with gastric juice produced by glands in the wall of the stomach.

Gastric juice contains hydrochloric acid and enzymes (protease).

The hydrochloric acid - neutralises the alkali in the saliva - prepares an acidic medium for the enzymes to

act on the food. - It also kills bacteria in the food. - Activates the protease


Protease digests proteins into polypeptides and peptones.

Mucus protects the stomach walls The mixture of food and gastric juice formed

the chyme (semi solid food)

STOMACH


DUODENUM


DUODENUM

The duodenum is the first part of the small intestine. The food is mixed with bile and pancreatic juice. Bile: - a thick alkaline liquid produced by the liver and

stored in the gall bladder - does not contain any enzyme. - neutralises the acid in the food from the stomach

(acidic chyme) - Emulsifies oil into droplets so that it is easier for

any enzyme to act on it.


Pancreatic juice is very alkaline. It contains three enzymes — amylase,

protease and lipase. Amylase: changes starch into glucose Protease changes proteins into amino

acids. Lipase changes fats into fatty acids and

glycerol.

DUODENUM



SMALL INTESTINE


SMALL INTESTINE

The second part of the small intestine is called the ileum.

Digestion is completed in the ileum. Secretes the intestinal juice contains maltase,

protease and lipase. Maltase: breaks down maltose to glucose Protease: breaks down proteins and peptones

into amino acids. Lipase: breaks down fats into fatty acid and

glycerol


END PRODUCTS OF DIGESTION

CARBOHYDRATES

STARCH →MALTOSE → GLUCOSE

PROTEIN → POLYPEPTIDES / PEPTONES → AMINO ACID

FATS → FATTY ACIDS + GLYCEROL


ABSORPTION OF DIGESTED FOOD

Completed in the small intestine (ileum) The small intestine contains: (a) simple sugars (from the digestion of

carbohydrates), (b) amino acids (from the digestion of proteins), (c) fatty acids and glycerol (from the digestion of

fats), (d) vitamins and minerals (do not need any

digestion), (e) fibre (indigestible food), (f) water.


The digested food, vitamins and minerals are absorbed by structures called villi (singular: villus) on the inner wall of the intestine.

Villi are very tiny projections; increase the surface area for the absorption of food.

Villi are richly supplied with blood vessels to carry away the absorbed food substances to all parts of the body.


VilliVilli


Digested food absorbs to the bloodstream by diffusion → liver → heart → all over the body

During respiration, glucose is oxidised in the cells to release energy, with carbon dioxide and water as waste products.

During assimilation, amino acids are used to build new cells or repair damaged cells.


Excess glucose is stored as glycogen in the liver.

Excess amino acids are decomposed (deaminated) by the liver into urea and excreted in the urine.

Excess fats are stored under the skin or around organs such as the heart and kidneys.


REABSORPTION OF WATER AND DEFECATION


The digested food substances have been absorbed by the small intestine.

The residue consist of water, undigested food, mucus and digestive juices. Bacteria are present in large numbers in the large intestine.

The colon of the large intestine absorbs the water , vitamins and mineral salts from the food residue, leaving behind solid waste material (faeces)


The faeces is stored in the rectum and will be thrown out through anus by the action of the muscular wall.

The process of getting rid of the faeces from rectum is known as defecation.


CONSTIPATION

Difficulty in removing undigested food from the. Can be avoided by eating food rich in fibre

(roughage), drinking plenty of water and exercise regularly.

Roughage helps the food to pass through easily Without roughage, the food will move slowly and

contains in the large intestine longer in time Can cause cancer, piles


EATING HABITS

We should also chew the food well before swallowing it.

We should eat clean healthy food. Food contaminated with bacteria can cause

diarrhoea and food poisoning. Diarrhoea makes the intestine incapable to

reabsorb the water Lead to dehydration


HEALTHY EATING HABITS

Unhealthy eating habits leads to: Cardiovascular disease Cancer Obesity High blood pressure Anorexia nervosa




Something to think….Something to think….

The generous distribution of food for The generous distribution of food for under privilegesunder privileges

Cultural practices in dining Cultural practices in dining conforming to sensitivities and conforming to sensitivities and religious beliefs.religious beliefs.

Education

Nutrition f1 igcse