2. DIET
Means what you eat
The food is the source of raw materials that
needed to make new substances for:
Energy Growth and Health
(helps us to move) repair
4. Carbohydrates
• Carbohydrates are good source of energy &
• it supplies most of the energy that we need.
• It is made up of the elements of carbon,
• oxygen and hydrogen.
• Carbohydrates can be divided into 3 groups:
(a) Monosaccharides
- glucose, fructose and galactose
(b) Disaccharides
- maltose, lactose and sucrose
(c) Polysaccharides
- starch, glycogen, cellulose
5. Monosaccharides are carbohydrates which
cannot be broken down into simpler forms.
Glucose Fructose Galactose
Found in Sugar Sweet fruits Milk
6. Disaccharides are created when two
monosaccharides become linked.
Sucrose Maltose Lactose
(Glucose + (Glucose + (Glucose +
Fructose) Glucose) Galactose)
Found in Sugarcane, Sprouting Milk
sweet fruits grains
7. sugar
• Sugars are used to make
chocolates, candies, soft
drinks and cakes.
• Excess carbohydrates in
the body are converted
by the body into fats.
8. Polysaccharides are long chains of monosaccharides
and are the most common carbohydrates in nature.
Storage Structural
Polysaccharides Polysaccharides
- Stored for future - To maintain the shape
use and integrity of the plant
Starch Glycogen Cellulose
Found Plants Animals Plants
in
9. starch
• Starch is found in food such as rice, potatoes, bread,
cereals, noodles, yam, cassava, beans and grains.
11. OBESITY
• Excess carbohydrates
are turned into fats and
stored under the skin
which will cause
someone to be
overweight (obese)
• This condition increases
their risk of heart
attack in the future.
12. Stroke Other
complications
due to obesity
Blood vessel damage
(arteriosclerosis)
Heart attack
Kidney failure
13. ANOREXIA
• Someone who is
seriously
underweight is
called anorexic.
• This happen when
they don’t eat or eat
less than what they
need.
• They will feel weak
and tired all the time
because they do not
have enough energy.
15. fats
• Fats give more than
twice the energy as
the same amount of
carbohydrates.
• Functions of fats:
- reserve supply of
energy when we
don't eat
- are kept under our
skin to keep us warm
16. • Fats are obtained from 2 main sources:
(a) Animals
- milk, cheese, butter and eggs.
(b) Plants
- peanut oil, palm oil, olive oil
17. Are fats bad for us?
Not all fats are bad for
our health. There are
2 types of fats:
(a) Saturated fats
- These fats are known
for blocking coronary
artery in the heart,
which eventually
leads to heart attack
(b) Unsaturated fats
- Some fish oils are
thought to reduce the
growth of fatty
deposits in arteries.
18. Saturated fats Unsaturated fats
Found in Cheese, butter, Vegetable oil, olive
animal fats, egg oil
Effects blocking coronary reduce the growth
artery in the heart, of fatty deposits in
which leads to heart arteries.
attack.
20. HEART ATTACK
• Fats can caused
someone to be obese.
• Some fats can block
our blood vessels in
the heart and cause
heart attack.
• The fats can also block
the blood vessels in
the brain and cause
stroke.
23. Proteins
• It consists of long
chains of amino acids
which are made up of
the elements carbon,
hydrogen, oxygen and
nitrogen.
• Like carbohydrates and
fats, protein can supply
us with energy.
• However, their main
function is to build
body cells, tissues,
enzymes & hormones.
24. • They are essentials for
growth and repair of worn-
out parts of our bodies.
• Muscles, tendons and
cartilage in our bodies are
made up of proteins.
25. Proteins can be obtained from meat, eggs,
fish, milk, cheese, and beans
27. GOUT
• Proteins are broken
down to amino
acids.
• Excess of amino
acids will be turned
into uric acids.
• These uric acids will
accumulate in our
joints and cause
swelling and pain.
28. Swollen and Masses of
inflamed joint uric acids
Uric acid
crystals
29. Normal Kwashiorkor
KWASHIORKOR
• This condition
affects most of the
children from poor
countries.
• Such children
usually have
swollen abdomens.
• Their skin cracks
and becomes scaly.
32. Fibers
• Fiber is made up of
cellulose which cannot
be broken down by our
bodies.
• The right amount of
fiber in our diet keeps
out intestines healthy
and working properly.
• The lack of fibers in our
diet can caused
constipation.
33. • Vegetables, fruits,
brown rice, cereals,
whole wheat bread
are examples of food
which are rich in fiber.
34. Animals such as cows,
sheep and goats are called
ruminants. They are able
to digest cellulose with
the help of bacteria in
their stomachs, each of
which has four chambers
35. Vitamins
Types of Vitamins Diet Problems
Water-soluble Fat-soluble
- Vitamin B - Vitamin A
- Vitamin C - Vitamin D
- Vitamin E
- Vitamin K
36. vitamins
• Vitamins are needed in
small amounts by our
bodies for health and
growth.
• Vitamins are classified
according to:
(a) Water-soluble
-Vitamin B and C
(b) Fat-soluble
- Vitamin A,D,E,K
70. VITAMINS OVERDOSE
Vitamin pills are needed for certain groups such as young
children, senior citizen and pregnant women. Most of us
do not need vitamin supplements because we get all of
our vitamins from our diet. It can be poisonous to us!!
71. DEATH !!! A group of Italian
explorers, who had run
out of food ate the liver
of a polar bear they had
shot. Polar bear's liver
contains an enormous
amount of vitamin D
and these explorers
suffered the effects of
vitamin D poisoning,
which resulted in
several of them dying.
72. minerals
Types of minerals Importance Diet Problems
- Calcium To maintain
- Iron health
- Iodine
- Sodium
73. Minerals
• Minerals are substances
needed by the body in
tiny amounts for proper
growth and
development.
• They are needed in
some body tissues and
are used in some
chemical reactions of
the body.
74. CALCIUM
• Functions:
- building strong
bones and teeth
- muscles growth
and contraction
- clotting of blood
• Sources:
- dairy products,
green vegetables
and eggs
80. SODIUM
• Functions:
- regulating our body
fluids
• Sources:
- common salt
(sodium chloride)
• Excessive problem:
- high blood pressure
81. water
Importance Factors of intake:
- to dissolve things
Activity Environment
- fills up the cells
- helps to cool
down
82. Water
• Water plays vital roles
in many life processes.
• Almost 70% of our
bodies are made up of
water.
• We can survive
without food for
several weeks but we
would die in a few
days without water
83. • Water is needed for:
- To dissolve things so they
can be carried around our
bodies
- Fills up the cells so they
can maintain their shape
- Helps to cool down when
you sweat
- Acts as transporting agent
for digested food, wastes,
hormones and antibodies
84. • The amount of water needed in the body
depends on:
• (a) The activity of the person
• - people who are very active require more
• water than those who are less active.
85. (b) The environmental conditions
- people who live in hot conditions need more
water than those who are in colder environment.
86. • Water is lost from body daily during breathing, in
the urine, the feces and through sweating.
• To balance out the amount of water lost daily, we
need to drink about 8 glasses of water a day.
88. FOOD TESTS
CARBOHYDRATES FATS PROTEINS
STARCH SUGARS Emulsion Biuret's
test test
Iodine Benedict's
test test
89. IODINE TEST
To test the presence of starch
Iodine + starch → blue black
(orange) solution
NEGATIVE POSITIVE
90. Benedict's test
To test the presence of
reducing sugars
Benedict’s solution + food
(blue)
Heated in water bath
(5 mins)
Positive :
Blue → red brick precipitate POSITIVE NEGATIVE
91. BIURET's test
To test the presence of protein
Biuret’s solution + food
(clear)
Shake well
Positive :
Clear → purple NEGATIVE POSITIVE
92. emulsion test
To test the presence of fats
Ethanol + food
(clear)
Heated in water bath
(5 mins)
Positive :
Clear → white milky emulsion NEGATIVE POSITIVE
94. A Balanced diet
A balanced diet contains the right amount of energy,
carbohydrates, proteins, fats, fibre, vitamins, minerals
and water to meet the requirements of the body
95. ENERGY REQUIREMENTS
• Different individuals need
different amounts of
energy.
• The factors that affect
energy requirements are:
(a) Age
(b) Gender
(c) Activities
(d) Environment
(e) Special needs
96. AGE GROUP
A teenager and an adult need more energy
than a child or a baby
Children Adults
97. BODY SIZE
A big person needs more energy
than a smaller person
98. GENDER
A boy needs more energy than a girl.
A male adult needs more energy than a woman.
106. digestion
• Digestion is the process
of breaking down large
food molecules into
smaller molecules that
can be readily absorb by
the body.
• Digestion occurs in
alimentary canal, starts
from the food entering
our body through mouth
and exit from body
through anus.
107. Human digestive system
Mouth
Mouth
Tongue Pharynx
Esophagus
Esophagus
Stomach
Small intestine Liver Stomach
Gall bladder Pancreas
Large intestine
Large intestine Small
Anus intestine
Rectum
Anus
108. TYPES OF DIGESTION
Physical Digestion Chemical Digestion
Mechanical breakdown Involves the use of
of food by chewing action enzymes to break
of teeth and churning down food substances
of the stomach
109. Enzymes
• Enzymes are special
types of proteins
produced by our
body for bringing
about and speeding
up chemical
reactions in the
body.
• Enzymes that
breakdown food
substances are called
digestive enzymes.
110. • Different types of digestive enzymes help to break
down different nutrients into smaller and soluble
molecules
• Enzymes have an active site which is compatible to
one specific substrate (food)
Substrate Products
Enzyme Active site
111. Substrate Products
Bonds in the substrate
are weakened
Active
site
Enzyme Enzyme-Substrate Enzyme
Each type of Once the Then, the
enzyme has a substrate is bound products are
specific active to the active site, released & the
site, where only one the bonds in enzyme is ready to
type of substrate substrate are bind with another
can bind to it. weakened. substrate again.
113. DIGESTION IN MOUTH
• Food is broken down
into smaller pieces by
the teeth.
• Breaking up the food
into smaller pieces
increases the surface
area of the food for the
digestive enzymes to act
on.
• The food is then mixed
with saliva, produced in
the salivary gland. Salivary gland
114. • Saliva contains salivary amylase (an enzyme)
which catalyses the breakdown of starch into
maltose molecules.
• However, the food is usually not kept long enough
in the mouth for all the starch to be broken down
into simple sugar.
Amylase
Digestion
Starch molecule Maltose molecules
115. • The tongue rolls
the partially
digested food
into small balls
called bolus
before
swallowing.
• Then the tongue
pushes the bolus
toward the
pharynx (throat)
and into the
esophagus
116. OESOPHAGUS (GULLET)
• Oesophagus is a
narrow tube with
strong muscles in
its wall, connecting
the mouth and the
stomach. Oesophagus
• The bolus is pushed
along the Stomach
esophagus to the
stomach by
peristalsis.
117. • Peristalsis is
the involuntary
wave-like
muscular
contraction and
relaxation in
the esophagus. Muscular
contractions of
• No digestive digestive tract
enzymes are (peristalsis)
produced here.
118. DIGESTION IN STOMACH
• The stomach have Oesophagus Fundus
sphincter muscles to
Lower
control the flow of
esophagael
food in and out of
sphincter
the stomach.
Pyloric
• Functions of sphincter
stomach:
– Stores food for 2 to 6
hours
– Peristalsis and churning
actions break apart
the food substances.
119. • Stomach secretes gastric juices which contains
hydrochloric acid and proteases
• Functions of hydrochloric acid are :
• Stop action of salivary amylase
• Provides acidic medium for action of enzymes
• Change the inactive form of enzymes into an
active form.
• Kills most of the microorganism in food
120. • The gastric enzymes are produced as inactive
proteases
• Proteases catalyse the breakdown of proteins into
polypeptides and peptones.
Proteases
Proteins Polypeptides
121. • Mucus in the stomach
protects the stomach
wall from being
destroyed by acid and
proteases.
• Food is then gradually
converted to semi-
fluid substance called
chyme.
• Chyme is pushed into
the duodenum.
122. THE LIVER
• The main function of
liver in digestion is
to produce bile.
• Bile is a brownish- Liver
green liquid which
contains bile salts
and bile pigments.
• Bile is stored in gall
bladder and Bile
released into the duct
duodenum through
bile duct.
Gall bladder
123. PANCREAS
• Pancreas produces
pancreatic juice
which is released Pancreas
into the duodenum Pancreatic
through pancreatic duct
duct.
• Pancreatic juice
contains enzymes
such as:
- Lipase Bile duct
- Proteases
- Amylase Duodenum
124. DIGESTION IN DUODENUM
• The duodenum Bile from Bile from
connects the gallbladder liver
stomach & the
small intestine.
Pancreas
• It receives bile
from the liver
Bile
and pancreatic
duct
juice from
pancreas.
Duodenum
125. • Functions of bile:
- Neutralizes acidic
Lipid Bile
chyme from stomach
salts
- Emulsify fats into oil
droplets for lipase to
act upon
Increase
surface
area
126. Functions of pancreatic juice are:
- Neutralizes acidic chyme
- Contains digestive enzymes:
Enzyme Action of the enzyme
Pancreatic Starch maltose
amylase
Proteases Proteins Polypeptide
Lipases Fats fatty acids and glycerol
127. DIGESTION IN SMALL INTESTINE
• The small intestine consists
of three sections:
DUODENUM
connects to the stomach
JEJUNUM
the longest part
ILEUM
attaches to the first portion
of the large intestine.
128. • Tiny glands in small intestine produce intestinal juice
which contains several types of digestive enzymes:
Enzyme Action of the enzyme
Maltase Maltose glucose
Protease Polypeptides amino acids
Lipase Fats fatty acids and glycerol
129. SMALL INTESTINE VILLI
Veins to
the liver
Layers of Lumen
muscles
Blood
capillaries
Villi
Lacteal
130. ABSORPTION OF DIGESTED FOOD
• Absorption is the movement
of digested food through the
wall of small intestine.
• It takes place because of
diffusion. Lacteal
• Diffusion is the movement of
the molecules from higher Blood
concentration to lower capillary
concentration.
• The internal surface of the
small intestine is covered
with villi.
131. • The villi increase the
surface in contact with
the digested food, so it
can absorb faster.
• The walls of small Lacteal
intestine are richly
supplied with blood
vessels to carry away the Blood
digested food. capillary
• The fatty acids & glycerol
will diffuse into lacteal.
• The glucose & amino
acids will diffuse into the
blood vessels.
132. LARGE INTESTINE
• Large intestine does
not secrete any
enzyme.
Large
• Water, minerals and intestine
vitamins are absorbed
by large intestine.
• The undigested and
unabsorbed matter
are discharged as
faeces through anus.
133. • This process of discarding
faeces through anus is
called defecation.
• If the undigested food
passes through the large
intestine too slowly, too
much of water will be
absorbed.
• The faeces will become
hard and dry.
• This condition will leads
to constipation.