apter 6
Ch
Skin: Your Protective
Covering
It is not just your bones and muscles that support and
protect your body. Your skin also does this. Your skin is the
largest organ in your body. It provides you with a waterproof
cover, and holds all the systems in your body safely inside. As
well, it helps to prevent infections from entering your body.
Infections can enter your body if you have a cut or scrape on
your skin.
Your skin has different layers. The top layer is where new
skin cells are made. They are made at the bottom of the top
layer and move to the surface of your skin. By the time they
get to the surface, they are dead. Then they flake off. In fact,
you lose 30 000 to 40 000 dead skin cells every minute of every
day. By doing this, your skin is always replacing itself so that it
can protect you better.
Skin cells flaking off
Top layer
of skin
Skin cells moving
to top layer of skin
왖 It is important to wash your skin to remove dead skin cells and dirt.
Did you know that your nails and your hair are part of
your skin? They grow from one of the lower layers. Both
your nails and your hair protect your body. It’s easy to see
how your nails protect the ends of your fingers and toes, but
how does your hair protect you?
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You have hair on nearly every part of the outside of your
body. Some places that do not have hair are your lips, the
palms of your hands, and the soles of your feet. The hair on
your head helps to keep your head warm and protects your
skull, like a cushion. Your eyebrows protect your eyes from
sweat that could drip into them. Your eyelashes help to stop
things such as dust from getting in your eyes.
You will grow about
15 m of fingernails in
your lifetime. You will
also grow about 1 km
of hair.
Compare Fingerprints
Skills Focus: observing
Each person has unique skin patterns on their fingers called
fingerprints. Your fingerprints mark you as different from every
other person in the world. This is why fingerprints are used to
identify people.
1. Rub a pencil on a piece of paper until you have a dark
smudge, about 2 cm by 2 cm.
2. Rub the tip of your left index finger on the pencil smudge until
it is covered with the pencil lead.
3. Place a strip of clear tape over your fingertip lengthwise.
Press down gently on the tape.
4. Carefully remove the tape, and stick it on a piece of white paper.
5. Use a magnifying glass to examine your fingerprint.
Compare your fingerprint with other students’ fingerprints.
Are they all different?
1. What are two important jobs of your skin?
2. How does your skin keep itself new? Why do you think this is
important?
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