Respiration and Excretion
Lt: I can describe the parts of the respiratory system.
Respiration and Excretion
Have you ever been outside when the air was so cold you see
your breath? All humans breathe. Breathing is important for
cellular respiration, which releases oxygen from food. When
you breathe in you take in oxygen. This oxygen is used in
cellular respiration. When you breathe out, you get rid of
carbon dioxide. Breathing out is part of excretion, or the
removal of waste products from the body. When you see
your breath on cold days, you are seeing some of the waste
products of respiration.
The Respiratory system
Each time you breathe in, your lungs fill with air.
The lungs, tubes, and passageways through which
air moves in your body make up the respiratory
system. The job of this system is to take oxygen
into the lungs and to get rid of carbon dioxide and
water.
Passages to the Lungs
Air enters your body through your nose and mouth.
Then, air moves into your throat and enters the
trachea, or windpipe. The trachea is a tube about 10
cm long. The end of the trachea divides into two
smaller tubes. These tubes are the bronchi. Each
bronchus extends into a lung.
Lungs
The lungs are the main organs of the
respiratory system. In the lungs, the bronchi
divide many times. The tubes become smaller
and smaller. At the ends of the smallest tubes
are microscopic air sacs. These air sacs are
called alveoli. Each lung contains about 150
alveoli.
Larynx
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At the top of the trachea is an organ called the larynx. It is made up of
cartilage.
The human larynx contains two thin folds of skin called vocal cords.
Larynx
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During normal, quiet breathing the vocal cords are relaxed. However,
when you speak, your vocal cords tighten.
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As you breathe out, air passing over the vocal cords causes them to
vibrate and produce sounds. When you swallow, a flap of tissue called the
epiglottis, automatically closes the larynx. This prevents the food and
liquid from entering the windpipe. If food or water does enter the
windpipe, the cough reflex usually forces the material out.
Health and Safety Tip
Asthma
Many people suffer from asthma. Asthma usually caused by an
allergy to airborne particles. The muscles react by getting
narrower. Air cannot pass easily into and out of the alveoli.
Particles in the air can also cause the lungs to produce mucus.
Breathing becomes very difficult. Drugs prescribed by a doctor
often are used to help relax muscles in the air tubes, allowing
them to open up.