The Respiratory System
The main function of the respiratory
system is to supply your blood with oxygen
so that the blood can deliver this oxygen
to all parts of the body. We do this through
breathing - we inhale oxygen and exhale
carbon dioxide, both of which are usually
involuntary and automatic. This exchange
of gases is the respiratory system’s way of
getting oxygen to the blood.
When you breathe in, the air enters in through
your nasal cavity or mouth. It is then warmed
and cleaned. From there it heads through the
pharynx, where your tonsils intercept any harmful
organisms and destroy them.
From here, the air then passes through your
larynx. The epiglottis, the upper part of the larynx,
stops food from going through into the larynx
when you are swallowing. The air then follows into
the oesophagus.
As it goes down the air reaches the trachea, also
known as the windpipe, which is a tube lined with
cilia that transports the air in and out of the lungs.
The trachea has rings of cartilage all the way along
it that prevent it from being squashed or crushed.
Cilia are special hairs that prevent dust or dirt
getting into the lungs. They move back and forth,
carrying mucus up and out. Mucus, which is a
sticky fluid, collects the dust and we expel it when
we sneeze, cough, spit or swallow.
The trachea branches out into two main bronchi,
and each of these is divided into smaller branches,
called bronchioles, and then into pulmonary
alveoli, which are like little sacks where the gases
are exchanged.
The oxygen passes into the blood at the alveoli
and then is transported to the tissues all over the
body. The carbon dioxide passes back from the
bloodstream into the alveoli to travel back up and
be exhaled.
12
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Your diaphragm is a sheet of muscles that lies across
the chest cavity – it helps to push the carbon dioxide
out and pulls the oxygen in. As the diaphragm contracts
and relaxes, breathing takes place. When the diaphragm
contracts, oxygen is pulled into the lungs. When the
diaphragm relaxes, carbon dioxide is pumped out of
the lungs.
Why do we yawn?
When you are too tired, your lungs do not take in enough
oxygen from the air you inhale. This means you do not
have enough oxygen coming into your body, and when
your brain senses this shortage, it sends a message that
causes you to take a big long breath, or a yawn!
Why do we sneeze?
Sneezing is a bit similar to a cough, it helps to remove
something that is irritating the mucous membranes of
the nose.
What are hiccups?
This is when your diaphragm suddenly moves, and this
is involuntary. This can happen if your diaphragm gets
irritated, you eat too quickly or many other things. When
you breathe in, the air enters in through your nasal cavity
or mouth. It is then warmed and cleaned. From there it
heads through the pharynx, where your tonsils intercept
any harmful organisms and \