Breathing and the respiratory system
Why do we have to breathe?
Our body is a very complex system. One of the main things it needs is
energy. When we eat our body digests the food to get complex molecules
like glucose, which it can use for energy. However, food alone isn't
enough. The cells also need oxygen to react with the glucose to create
the energy. We get the oxygen to our cells with the respiratory system
and by breathing.
We breathe in using a muscle called the diaphragm. It flattens out
making our lungs expand and fill with air. When we breathe in, air gets
forced through our nose or mouth, down our windpipe, and into bronchi
tubes in our lungs. These bronchi tubes branch out and get smaller and
smaller, like the roots or branches of a tree.
At the end of the smallest branches of the bronchi are tiny air sacs
called alveoli. These air sacs have a very thin, one cell thick wall
that allows oxygen to be passed on to red blood cells as they are
passing by. There are hundreds of millions of these tiny guys in our
The alveoli don't just pass oxygen to our blood, they also help to
clean out waste gas from our blood cells. This waste gas is carbon
dioxide. When we need to breathe the carbon dioxide out of our lungs,
the diaphragm bows up and pushes the air back out, getting rid of the
carbon dioxide. This makes room for fresh air with new oxygen to come
back in on our next breath.
The nose does more for breathing than just providing a place for air
to enter our body. It also helps to filter the air of dust and other
stuff. It does this by using lots of hairs and mucus. It also helps warm
up the air prior to getting to our lungs.
Why do we get out of reath?
When we run or do strenuous activity, our muscles burn energy and use
up the oxygen in our red blood cells. To try and get more energy and
oxygen into these cells, our heart will pump faster to get more blood
through the lungs. At the same time our lungs will try to breathe harder
and faster to get more oxygen. We end up feeling out of breath and have
to take a rest so our bodies can recover.
The respiratory system also helps with talking. We couldn't talk
without air. By forcing air through our vocal chords, the respiratory
system helps them to vibrate and create sound like talking, singing, or