Front | Back |
Airflow is governed by the same principles of......
as blood flow |
Flow, pressure and resistance
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Atmospheric pressure
|
Drives respiration--amt of pressure exerted from the atmosphere
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Intrapulmonary pressure
..also referred to as_______ |
Pressure within the lungs (alveoli)
aveolar pressure |
Direction of airflow depends on:
|
Gradient between atmospheric pressure and intrapulmonary pressure
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Negative pressure:
|
Implies below atmospheric pressure
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Positive pressure:
|
Implies above atmospheric pressure (out of the lungs)
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Boyles law
|
Pressure of a gas in a closed container is inversely proportional to the volume of its container at a constant temperature
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Charles' law
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Volume of a gas in a close container is directly proportional to its absolute temperature at a constant pressure
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Dalton's law
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Each gas in a mixture exerts its own partial pressure independent of the partial pressures of the other gases in the mixture
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Henry's law
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The amount of gas that dissolves in a liquid is directly proportional to its solubility in that liquid and its partial pressure
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Inspiration
--for air to flow into the lungs ...this is accomplished by |
Intrapulmonary pressure must be less than atmospheric air pressure
...increasing volume of the lungs |
When diaphragm and external intercostal muscles contract:
|
Volume of thoracic cavity increases
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Contraction of the diaphragm:
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Increases volume of the thoracic cavity from top to bottom
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Contraction of external intercostal muscles:
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Pulls ribs upward and outward to increase volume of thoracic cavity from front to back
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Consequences of contractions:
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Because visceral and parietal pleurae adhere strongly to one another, lung volume will expand as volume of thoracic cavity expands
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