By Ms. Musich
Functions of the Respiratory
System
 1) Moves oxygen from the outside environment into
the body,
 2) Removes carbon dioxide and water from the
body.
This is a cartoony image of
your lungs, the main organs
of the respiratory system!
Why the Body Needs Oxygen
 Your body needs oxygen to keep you alive, right?
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But why?
Oxygen is a key player in respiration.
Respiration is not breathing!
Respiration is the process in which oxygen and
glucose undergo a complex series of chemical
reactions inside cells.
This process of respiration is how your body
creates energy for itself! Pretty cool, huh?
Homeostasis in Action!
 Remember this funny word?
 Now we know that our respiratory system inhales
oxygen for us when we breathe, but that oxygen
wouldn’t go anywhere without the help of our
circulatory system.
 Also, our bodies couldn’t carry out respiration
without glucose (sugar) that our digestive system
breaks down.
Did You Know?
 The air you are breathing in right now is made of
a mixture of gases.
 Only about 21% of the air is oxygen.
 78% is nitrogen.
 What percentage are we up to?
 The remaining 1% is made up of carbon dioxide,
helium, and various other gases.
Elements are pure
chemical substances
Path of Air
Path of Air
 Luckily, your respiratory system is equipped with
tools so that less of that stuff gets in your lungs.
 As air travels from the outside environment to the
lungs, it passes through the following organs :
nose, pharynx, larynx, trachea, and bronchi.
 It only takes a few seconds!
Nose Functions
 Heats the air you breathe in.
 Produces mucus that traps dust and bacteria.
 Contains cilia (hairs) that sweep the mucus into
the throat
 Causes you to sneeze so that dust particles and
bacteria leave the body.
Pharynx (FAR ingks)
 Known as your throat
 Shared with the digestive system
 Both nose and mouth connect at the pharynx.
Trachea (TRAY kee uh)
 Known as your windpipe.
 Made of thick rings of cartilage that remain firm
to strengthen the trachea and keep it open.
 Why do you think it’s not squishy like the
esophagus?
 Also lined with cilia and mucus
 Allows you to cough if there are dust or bacteria
irritating your windpipe.
Bronchi & Lungs
 Bronchi are the two main branches that lead to
the lungs
 Bronchitis sound familiar?
 Each bronchus leads into a lung where it branches
out into smaller and smaller branches.
 At the ends of the smallest tubes are bundles of
“grapes” called alveoli.
 Alveoli are tiny sacs of lung tissue specialized for
the movement of gases between air and blood.
Gas Exchange
 After air enters the alveoli, oxygen passes through
the wall of the alveoli and through the wall of a
tiny blood vessel. Carbon dioxide and water pass
from the blood into the alveoli.
Diaphragm
 A large dome-shaped muscle that plays an
important role in breathing located at the base of
the lungs.
 When you breathe in, the diaphragm moves down.
 When you breathe out, the diaphragm moves up.
Larynx (LAR ingks)
 Known as the voice box at the top of your trachea.
 Holds your vocal chords which produce your voice.
 Think of the way a balloon squeaks when you let
air through the neck. That’s kind of how your
vocal chords work.
 Muscles makes your vocal chords contract and the
movement makes the air molecules vibrate and
create a sound!