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UNIT 1

My name:

____________________

My class:

______________

School year:

_________________

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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

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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.

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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.

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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

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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.

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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. ______________________

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10. _____________

11. ______________________

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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_____

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3. How do they sound? Match the sounds to the pictures. Use colours to match.

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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.

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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.

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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.

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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? ______________________________________.

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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

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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

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