Lung volume

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Lung volume
Air flow thru trachea
Lung (alveolar) pressure
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Vertical axis lung volume
Speech
Quiet breathing
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Respiration cant be understood without
appreciating the role of lung recoil
forces. Elasticity of lung tissue exerts a force
that drives toward smaller lung volumes. Thorax
exerts a force that drives toward larger lung
volumes.
The combined effect of lungs-thorax is shown to
right. Net effect can be viewed as a single
spring the balance point of lung and thorax
springs.
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Lungs are often viewed as two elastic bags two
balloons. Not accurate physiologically since
lungs have a complex internal structure, but
functionally, the elastic-bag view will work just
fine for us.
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Viewing the lungs as a bellows also works
again, from the point of view of function, not
anatomy.
Inhalation Pull outward (a) volume increases,
pressure decreases (re atm. pres.), air flows
inward. Exhalation Pull inward (a) volume
decreases, pressure increases (re atm. pres.),
air flows outward.
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• There are 12 ribs.
• They attach to thoracic vertebrae in back, and to
  the sternum in front.
• Ribs attach to the costal cartilage, which
  attaches to the sternum.
• Arch-shaped bones slope downward at rest.

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Major Muscles of Inspiration
Diaphragm
External Intercostals
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More Inspiratory Muscles Note the direction of
these muscle forces they spread the ribs,
increasing lung volume.
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Still more inspiratory muscles
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Major Muscles of Expiration
These muscles (a) pull down on the ribs, (b)
squeeze in on the abdomen, or (c) both. Results
Decrease in lung volume, increase in lung
pressure, outward airflow (exhalation).
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More Expiratory Muscles Note the downward pull
of these muscle forces.
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Why Recoil Forces Matter
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Muscle Activity During Expiration
Note that inspiratory muscles are active during
the initial phase of the expiration. When the
elastic recoil forces of the lung-thorax unit
reach their resting state, expiratory muscles
take over to effect further decreases in lung
volume. The inspiratory force that is applied
decreases over time. The expiratory force that is
applied increases over time.
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Push on chest
Moral Respiratory force affects vocal intensity,
but it also affects voice pitch.
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Push on chest
Why does f0 increase with higher respiratory
force? The effect is entirely aerodynamic the
increase in respiratory force increases particle
velocity. Since it is the particle velocity
increase that is responsible for the Bernoulli
force, there is an increase in the size of the
Bernoulli force. The increase in the magnitude of
the Bernoulli force causes the vocal folds to
return to midline more quickly, which shortens
the fundamental period, increasing f0.
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Push on chest
Is This a Fact Thats Worth Knowing? Suppose you
have a voice client who would benefit from
increasing voice pitch (especially due to glottal
fry). What are the options for increasing f0?