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Respiratory System
Respiratory surfaces
must be moist for
gas exchange
Larynx=voice box
Trachea=windpipe
Air sacs for gas
exchange=alveoli
Right lung: Three lobes
lobes
Left lung: Two
How do you breathe?
• Your diaphragm contracts, moving downward.
This increases the volume in your lungs,
therefore decreasing the pressure.
• Air moves from high pressure to low pressure,
so air flows into your lungs. You inhale. This is
called NEGATIVE PRESSURE BREATHING
• Your diaphragm then relaxes, moving back up
and decreasing lung volume. This increases
lung air pressure, causing the air to flow out of
your lungs.You exhale.
Inhaling and exhaling
• Vital capacity is the maximum amount
of air that we can inhale or exhale-See
model
Cilia help to clean air as it passes
They constantly beat upward.
Vocal Folds
•Functions
–Epiglottis prevent swallowed material from moving into larynx
–Vocal folds are primary source of sound production
Where does gas exchange
happen?
• In the alveoli
• They are moist air sacs in the lungs
• Oxygen goes from the air space in the
alveoli to the capillaries to the blood
stream, while carbon dioxide goes from
the blood stream cappillaries to the alveoli
air space to be expelled as a waste
So what happens to your lungs
when you smoke?
• You can get emphysema, where the alveoli walls
become brittle and less “springy”
• This reduces vital capacity
• They can even rupture, reducing the amount of area for
gas exchange.
Blood flow
• Major route brings deoxygenated
blood to the lungs via the
pulmonary artery (artery=AWAY
from heart), to pulmonary
capillaries, is oxygenated and
returns to the heart through the
pulmonary veins (to heart).