The skeletal system gives the body its structure and shape through bones of varying sizes and joints that allow movement. Bones contain living cells that help them repair if broken. The rib cage protects the heart and lungs. The digestive system breaks down food through teeth, stomach acids, and the small intestine before waste is passed through the large intestine and rectum. The tongue's bumps and taste buds allow for flavor detection. The circulatory system pumps blood through arteries and veins using the heart. Blood carries oxygen, nutrients, waste, red blood cells, white blood cells, and platelets. The heart beats faster during exercise to supply more oxygen to muscles.

1. P6U1 The Body Machine Part I: Body Systems Dossier
The Skeletal system
Why do we have bones?
There are more than 206 bones inside us, all
joined together to make up our skeleton. Our
skeleton gives our body support and shape. Bones
are different sizes and shapes, depending on the
work they do. Our thigh bones or femurs are the
largest bones in our body. They are long and
strong to support the weight of our body
whenever we stand up, run, walk or jump.
The head bone is called skull, and it protects our
brains.
How do bones fit together?
Most of our bones are linked by joints so they can move in different
directions. The knee joint is where the curved bottom of the femur fits
into the curved top end of the tibia. The ends of the bones are covered in
slippery fluid so the knee can move backwards and forwards smoothly.
What happens if you break a bone?
Bones contain living cells that help them grow longer and stronger as you
grow. If you break a bone, the cells repair the damage and the bone mends
itself. Sometimes, a doctor sets the broken bone in a hard plaster cast to
stop it from moving. This helps the bone to mend in the correct position.
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2. P6U1 The Body Machine Part I: Body Systems Dossier
What does the rib cage do?
It acts as a shield that protects the heart and lungs.
Both men and women have 12 pairs of ribs.
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Amazing!
Nearly half the bones in our body are in
our hands, feet, wrists and ankles!
We have exactly the same number of
neck bones as a giraffe!

3. P6U1 The Body Machine Part I: Body Systems Dossier
The digestive system
Why do we need to eat?
We cannot live without food. It gives us energy and makes us grow. Before
our body can use the food we eat, it has to be broken down into tiny pieces,
so that nutrients are small enough to pass into our blood. This process is
called digestion. Our digestive system starts in our mouth.
Where does food go?
Our teeth and saliva break down food in our mouth. Then, we swallow the
food and it goes down a tube called esophagus to our stomach. There it is
mixed with chemicals to make a thick soup. Then this mixture travels slowly
along a long tube called the small intestine. Nutrients pass through its thin
walls into our blood to go round our body. The remaining food travels to our
large intestine, which absorbs water. Solid wastes are stored in our rectum
until we go to the toilet.
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4. P6U1 The Body Machine Part I: Body Systems Dossier
Why is the surface of our tongue bumpy?
If you look at your tongue in a mirror, you
can see small bumps on it. Around the bumps
there are taste buds. They detect flavours.
There are four different types of taste
buds. Each type is on a different part of
our tongue and detects a particular kind
of taste.
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Amazing!
On average, a person eats 30 tonnes of
food and drinks 50.000 litres of liquid
during their lifetime!
Our tongue has more than 10.000 taste
buds on its surface!

5. P6U1 The Body Machine Part I: Body Systems Dossier
The respiratory system
How do we breathe?
We breathe automatically because our
body needs oxygen to stay alive. Our
lungs are like sponges full of tiny air
tubes. When we breathe in, our lungs
swell up as air fills the tubes. Oxygen
passes out of the tubes into our blood
to travel around our body. At the
same time, a waste gas called carbon
dioxide passes from our blood into our
lungs. Our lungs shrink again as we
breathe air out.
What does our nose do?
We breathe in air through our nose
and down our windpipe to our lungs.
Our nose warms the air we breathe in,
mucus and hairs inside it also trap dirt
to stop it reaching our lungs. A small
area at the top of our nose is full of
nerve cells that detect smells in the
air. These give us our sense of smell.
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Amazing!
We take about 23.000 breathes every
day!
The nerve cells in our nose can detect
10.000 different smells!

6. P6U1 The Body Machine Part I: Body Systems Dossier
The circulatory system
How does blood flow?
Blood flows around our body all
the time, carrying oxygen and
food to the cells and taking
away waste. Our blood is
pumped along by the heart, an
organ with strong walls of
muscle. First, the blood is sent
to our lungs to collect oxygen,
then it returns to our heart and
is pumped to the rest of our
body. The tubes that carry
blood away from the heart are
called arteries. Those that
carry blood back to the heart
are called veins.
What is blood made of?
More than half of our blood is made of a
liquid called plasma. Floating in it are red
cells, white cells and platelets. The red
cells carry oxygen around our body. White
cells fight germs, to protect our body from
infection. Platelets help our blood to clot
and form a scab if we cut ourselves and
bleed.
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7. P6U1 The Body Machine Part I: Body Systems Dossier
Why does our heart sometimes beat fast?
When we cycle or do any other exercise, our
muscles need extra oxygen to give us more
energy. Our heart beats harder and faster
to pump more blood to our muscles. We also
breathe faster to take in more oxygen, so
there is more oxygen in our blood.
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Amazing!
Our heart beats about 100.000 times a
day, every day of our life, without
getting tired!
An adult’s heart pumps 15.000 litres of
blood a day!

8. P6U1 The Body Machine Part I: Body Systems Dossier
The muscular system
What makes us move?
Every movement we make is made by muscles. We have
more than 600 different muscles. Many of them are
attached to our bones by strong tendons that allow us
to move. There are also muscles in our skin and eyes,
and others that keep our heart pumping and our
insides working.
How do muscles work?
When
we tense
a
muscle, it gets shorter and thicker. Most
muscles work in pairs. For example, we
tense the biceps muscle to bend our arm. To
straighten our arm, the triceps muscle
tenses and the biceps muscle relaxes.
Why do dancers need to warm up?
For muscles to work well, they need a
good supply of blood and oxygen.
Dancers and athletes do gentle
exercises to loosen their muscles
before they start exercising. This
increases the blood flow to their
muscles, giving them more energy. If
we exercise hard without warming
up, we risk injuring our muscles.
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9. P6U1 The Body Machine Part I: Body Systems Dossier
9
Amazing!
Nearly half our body weight is made up
of muscles!
We use eight to twelve different
muscles in our face just to smile!

10. P6U1 The Body Machine Part I: Body Systems Dossier
9
Amazing!
Nearly half our body weight is made up
of muscles!
We use eight to twelve different
muscles in our face just to smile!