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All animals need oxygen
to live. Land animals get oxygen from the air. Without the
oxygen in the air we cannot survive more than a few minutes.
Breathing happens automatically, we do not have to even
think about it.
We breathe in order to take oxygen into
our bodies and get rid of carbon
dioxide. The oxygen is carried in
the blood to all the body's cells. The air we breath out has
100 times more carbon dioxide than the air we breath
in.
1.![](http://library.thinkquest.org/5777/images/lizcont2.gif)
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Nose and
Nasal Cavity
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![](http://library.thinkquest.org/5777/images/lizcont2.gif)
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![](http://library.thinkquest.org/5777/images/41a.gif)
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The respiratory system is made of body
parts that are in charge of your breathing. It includes your
nose and nasal cavity. You inhale air though your nose. As
you inhale,
small specks of dirt are trapped by many tiny hairs in your
nose. This cleans the air. The hairs stop the dirt from
going further in your body. The moist inside surface in your
nose traps even smaller pieces of dirt. The nasal
cavity, the air passage behind
the nose, plays an important role in breathing. The nasal
cavity is divided into a right and left passageway. The
tissue that covers the wall of your nasal cavity contains
many blood vessels. Heat from the blood in the vessels helps
warm the air as you breath. Moisture is added to the air you
breath by special cells in the walls of the nasal cavity.
The air is warmed and moistened before it reaches your
lungs.
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![](http://library.thinkquest.org/5777/images/41aa.gif)
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You usually cannot see the air
you breathe out. But on cold days the air you
exhale
is visible. This is because your breath contains
water vapor, as well as carbon
dioxide. As the water
vapor meets cold air, it condenses
and turns into tiny droplets of liquid water which
look like white puffs of steam. | |
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