science form 2 nutrition notes
TRANSCRIPT
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
1
CHAPTER 2: NUTRITION
Classes of Food
Carbohydrates
Fats
Proteins
Fibre
Minerals Vitamins
Water
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)
2
Pellagra (skin disease)
Anaemia (shortage of red blood cell)
Scurvy (bleeding gums)
Rickets (stunted growth) Goitre (swollen neck)
Kwashiorkor (lack of protein)
3
Balanced diet – Diet which contains all seven types of food classes in the right quantities & proportions.
4
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
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.
5
Human digestive system
3. Chemical digestion – breaking down food by enzymes.
4. Peristalsis – Contraction & relaxation of digestive tract to channel the food throughout the digestive tract.
6
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
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.
7
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.
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.
8
Reabsorption of water & defecation
Good eating habits
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.
9