When you breathe in, air passes through your mouth and
nose, down your windpipe and into your lungs. Your lungs fill with
air and your chest expands. This is the respiratory system at
work. Breathing is an involuntary action. This means the brain
takes care of it without any conscious effort on your part. The
respiratory system not only brings air into and out of the body, it also
brings oxygen to the blood.
When you breathe in, a thin sheet of muscle just below
your lungs, called the diaphragm, moves down. This action helps air
to enter your mouth or nose. The air is then moistened, warmed, and
filtered. Air then passes down the throat and moves past the voice
box. It travels down the windpipe, and into tubes in the lungs
called bronchi. The bronchi branch into smaller tubes and then into
millions of tiny air sacs called alveoli. The oxygen passes from the
air in the alveoli into the capillaries and is carried away by the
blood. Carbon dioxide is passed out of the body when you exhale.
Directions: Answer the questions about the
The respiratory system brings air into and
out of the body and
brings oxygen to the blood
passes carbon dioxide into the body
blood back to the heart
an involuntary action.
The beginning of the respiratory system is the
mouth and nose
The thin sheet of muscle just below the lungs is
Air travels down the windpipe, and into tubes in the lungs
The tubes in the lungs are called
Tiny air sacs in the lungs are called
What is passed out of the body when you exhale?
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