1
UNIT 1
My name:
____________________
My class:
______________
School year:
_________________
2
UNIT 1
THE FIVE SENSES
Your five senses are very important. You touch, hear, see, taste and smell in order to adapt
to a new environment (situation).
The five senses work together all the time so your body can work properly. Your brain is the
computer for your body. The brain interprets the information the senses get. We use our
senses to interact with the world around us.
1. Complete:
o The ………………………. are the organs of …………………………
o The ………………………. are the organs of …………………………
o The ………………………. is the organ of …………………………
o The ………………………. is the organ of …………………………
o The ………………………. is the organ of …………………………
tongue smell
hearing touch
nose sight
taste skin
ears eyes
3
2. Write the name of the sense:
The nose
The smell of a rose, perfume, freshly baked bread and cookies… these smells are all made
possible because our nose and brain. The sense of smell, called olfaction involves the
detection and perception of chemicals floating in the air.
The nose is the organ of smell. It is divided into different parts:
- The nostrils are holes where the air enters.
- The olfactory region is inside the nose.
4
HOW DO YOU SMELL?
The air carrying the smells enters the nose through the nostrils. It goes to the olfactory
region. This region gets information about the smells and passes the information to the
olfactory nerve. The olfactory nerve carries the information to the brain.
Taste
Our tongue is the organ we use to taste. Little pimples called taste buds cover the
tongue. These taste buds identify different tastes and send this information to the
gustatory nerves. The gustatory nerves take the information to the brain and the
brain says which flavor is.
There are 5 different flavous: Sweet, salty, sour, umami and bitter.
How exactly do your taste buds work?
Well, stick out your tongue and look in the mirror.
See all those bumps? Those are called papillae , and most of them contain taste buds. Taste buds
have very sensitive microscopic hairs called microvilli. Those tiny hairs send messages to the brain
about how something tastes, so you know if it's sweet, sour, bitter, or salty.
The average person has about 10,000 taste buds and they're replaced every 2 weeks or so. But as
a person ages, some of those taste cells don't get replaced. An older person may only have 5,000
working taste buds. That's why certain foods may taste stronger to you than they do to adults.
Smoking also can reduce the number of taste buds a person has.
5
When you have a cold or allergies, and your nose is stuffy, you might notice that your food doesn't
seem to have much flavor. That's because the upper part of your nose isn't clear to receive the
chemicals that trigger the olfactory receptors (that inform the brain and create the sensation of
flavor).
The olfactory system works together with your taste buds to create the true flavor of that
yummy slice of pizza by telling the brain all about it!
1. How do you think it tastes? Tick
Hearing
Hearing lets us distiguish sounds. We know if sounfd are high or low, soft or loud. We also
know what direction a sound comes from. We can tell if it was near or far away.
The ears are the organs for hearing. What Are Ears and What Do They Do?
The ear is made up of three different sections that work together to collect sounds and send
them to the brain: the outer ear, the middle ear, and the inner ear.
The Outer Ear: Collecting Sounds
The outer ear is made up of:
- the pinna or earflap: the pinna is the part of the ear you see on the side of your
head. It's made of tough cartilage covered by skin. Its main job is to gather sounds and
funnel them to the ear canal.
- the ear canal:
Noodles
Fish
artichocke Cake
lemon
100%
cocoa
Milk
chocolate
BITTER
SWEET
SALTY
SOUR
UMAMI
6
which is the pathway that leads to the middle ear. Glands in the skin of the ear canal
make earwax, which protects the canal by cleaning out dirt and helping to prevent
infections.
The Middle Ear: Good
Vibrations
The middle ear is an air-filled
cavity that turns sound waves
into vibrations and delivers
them to the inner ear. The
middle ear is made up of the:
- eardrum. That
separates the outer
ear of the middle ear.
Sounds hit the eardrum, making it move. This movement leads to vibrations of the
ossicles.
- Ossicles, three very small bones in the middle ear.
- Eustachian tube that connects the middle ear to the back of the nose and acts as a
pressure valve, so pressure stays balanced on both sides of the eardrum.
To hear properly, the pressure on both sides of your eardrum must be equal. When you go up or
down in elevation, the air pressure changes and you may feel a popping sensation as your ears
adjust. They adjust thanks to the narrow Eustachian tube.
7
The Inner Ear: Nerve Signals Start Here
In the inner ear is the cochlea, which is full of liquid. The vibrations make this liquid move and
the auditory nerve sends signals to the brain. The brain interprets the sound .The snail-shaped
cochlea changes the vibrations from the middle ear into nerve signals. These signals travel to
the brain along the auditory nerve. There are 3 little bones. This semicircular canals look like three
tiny connected tubes. It's their job to help you balance.
Process:
Your ears pick up and send information about sounds to your brain in the form of nerves impulses.
Sounds are collected in the outer ear by the ear flap. They are sent into the ear canal in the
eardrum. Three small bones in the middle part of the ear make sounds louder. In the inner part of
the ear the COCHLEA sends impulses to the auditory nerve which goes to the brain. The brain
receives impulses from the auditory nerve and gives meaning to the sound impulses.
1. Write the words
The canals are filled with fluid and lined with tiny hairs. The hairs
send your position information as signals through the nerves to your
brain. The brain interprets these signals and sends messages to the
muscles that help keep you balanced. When you spin around and
stop, the reason you feel dizzy is because the fluid in your
semicircular canals continues to slosh around for a while, giving your
brain the idea that you're still spinning even when you aren't. When
the fluid stops moving, the dizziness goes away.
1. ______________________
2. ______________________
3. ______________________
4. ______________________
5. ______________________
6. ______________________
7. ______________________
8. ______________________
9.
10. _____________
11. ______________________
8
2. Number the sentences in order
REMEMBER
Why do we have to ears?
We have two ears because the sounds hit one ear a fraction of a second before
the other, this helps you to tell what direction the sounds come from. A person
who cannot listen is called a deaf person. Deafness can be caused by many
reasons.
Then the ossicles vibrate too _________
The information goes to the brain _______
Sound vibrations go into the ear canal __1___
The cochlea detects the vibrations _____
The eardrum vibrates ______
The auditory nerve collects the information_____
9
3. How do they sound? Match the sounds to the pictures. Use colours to match.
10
Touch
OUR SKIN
The skin is the organ of touch. We use our skin to identify if something is hot or cold,
soft or hard, smooth or rough.
Our body is covered by skin. Did you know that the skin is the biggest organ in our body? It covers your whole body. All the skin would weigh about 3 or 4 kilograms all together; it is a giant, washable, stretchable, tough, water proof sensory apparatus covering your whole body. Touch is to use your skin to have physical contact with another objetc. Touch receptors are located in clusters around your skin. The most sensitive touch receptors are located at your face, back of your neck, chest, arm, fingers, soles of your feet and betwween your legs.
Every part of our skin had nerve endings that pick up information. They can detect
heat, cold, pressure, and pain. The nerves then send messages to the spinal cord. The
spinal cord sends these messages to the brain.
The skin is divided into:
Epidermis: Which is the outside layer of your skin: It has hairs and pores. Pores are
very important because they let us eliminate sweat.
Dermis: The inside layer of skin. It has blood vessels and nerve endings.
11
HOW DOES THE SENSE OF TOUCH WORK?
The nerve endings get different sensations when something touches the skin.
Theses sensations include pain, temperature, hardness and texture. The information passes to the
tactile nerves. These nerves carry the information to the brain. The brain tell us if it is hot, cold,
hard….
a) What organ is used for the sense of touch?
Sight Change your book with your partner. Look at your partner´s eye and make a picture of
his/her eye. When you finish change your books again.
12
PARTS OF THE EYE Eyes have different parts, some parts protect the eye, some are for us to see.
Parts that protect the eye:
- Eyebrows and eyelashes prevent things from entering the eye.
- Eyelids, there are two, the upper and the lower. The upper is bigger and opens and closes
when we blink. Your eyelids protect your eyes from dust and dirt and also keep light
out.
- Tear glands produce tears
Parts of the eye for us to see:
- The iris is the coloured part of the eye. It controls the amount of light that enters the
eye.
- The pupil is in the center of the eye, it is a small black circle. Light eners inside the eye
through the pupil.
- The lens is inside the eye, it is located behind the pupil and the iris, it helps to see
object in focus.
- The retina is at the back of the eye. The light entering the eye goes to the retina. There
is a very important nerve attached to the retina, the optic nerve. This nerve caries the
information to the brain.
A CLOSER LOOK
Look at one of your eyes in a mirror. The white part is the sclera and the colored part is the
iris. The small black spot in the center is the pupil. The pupil is a hole that lets light into the
eye. When it’s dark, your pupils open to let more light in.
13
HOW DOES THE SENSE OF SIGHT WORK?
Light reflects off an object. The light then enters the eye through the pupil. I travels in
straight lines through the lens. This lens focuses the light on the retina at the back of the
eye, so we see them clearly and not blurred. It makes a picture of the object on the retina but
this picture is upside down..
The retina has millions of optic cells. They detect light, shape, size and colours. It sends the
information to the optic nerve. The optic nerve collects the information and takes it to the
brain. The brain turns the image up and tell us what we are seeing.
People who cannot see are blind people. These people make extra use of their sense of touch,
aslo of the sense of hearing .
1. Write true or false:
1. The sclera is the colored part of my eye. _______
2. My eyelashes keep out light when I sleep. ________
3. My pupils open more when it’s dark. ________
4. My eyelids protect my eyes from dust. _______
5. The iris is a small black spot in my eye. ________
2. Complete the sentences:
The (1) ________ lets light into your eye. The (2) _______ focuses light on the (3)
___________. The (4) ______________ detect light and colours. Then the (5) _______
_________ takes the information to the brain.
4. Answer the questions:
• Where is the retina? ____________________________________________.
• How many optic cells does the retina have? ____________________________.
• What colour are your irises? ______________________________________.
14
ACTIVITIES
1. Think and draw one picture for each sense.
4.
2. Label the pictures.
SIGHT SMELL HEARING TOUCH TASTE
Now colour:
The RETINA: yellow
The IRIS: blue
The OPTIC NERVE: red
The PUPIL: black
The EYEBROW: brown
The EYELID: pink
15
3. Label this picture. Then cut out the texts and stick them under the correct
parts of the eye.
4. Name and colour
Now colour:
The THREE LITTLE BONES: yellow
The EARDRUM: blue
The COCHLEA: red
The EAR CANAL: orange
The OUTER EAR: brown
The AUDITORY NERVE: green
O_ _ _ _ EAR
I _ _ _ _ EAR
M_ _ _ _ _ EAR
16