Mechanics of Breathing Lesson

The Mechanics of Breathing
Outline for Today’s Class
1. Air is a Gas
2. Polio and the Last of the Iron Lungs
3. The Mechanics of Breathing
4. Model Building
5. Exit Slip
Air is a gas
Gases move from
areas of higher
pressure to lower
pressure or from
high concentration
to low
The Iron
What Structures
are involved in
Review of the Lungs
The pleura includes two
thin layers of tissue that
protect and cushion the
lungs. The very thin space
between the layers is
called the pleural cavity. A
liquid, called pleural fluid,
lubricates the pleural
cavity so that the two
layers of pleural tissue can
slide against each other.
Intercostal Muscles
and Ribs
The intercostal muscles and
ribs allow the ribcage and
chest cavity it expand. The
lungs expand to fill this
increased space. This also
helps to create negative
pressure in the intrapleural
The diaphragm is a
dome-shaped sheet of
muscle and tendon that
serves as the main
muscle of respiration
and plays a vital role in
the breathing process.
How do these
structures allow us
to breathe?
Exit Slip
1. Lowering the pressure in the pleural cavity
causes the lungs to __________.
2. Contrary to popular belief lungs are not actually
like large balloons, they are instead similar
3. Did your model work? If not what do you think
went wrong?