Gaseous exchange in mammals occur as a result of
inhalation (or inspiration) and exhalation (or expiration).
Inhalation is the breathing in air into the lungs
and Exhalation is the breathing out air from the lungs.During the mechanism of
gaseous exchange in mammals the following events occur:
|
Breathing
in (inhalation)
|
Breathing
out (exhalation)
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|
1.The
external intercostals muscles contract
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The
external intercostals muscles relax
|
|
2.The
internal intercostals muscles relax
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The
internal intercostals muscles contract
|
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3.
The ribcage is lifted outward and upwards
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The
ribcage moves inwards and downwards
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4.
The diaphragm contract and flattens
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The
diaphragm relaxes and become dome shaped
|
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5.
the volume of the thoracic cavity increase as the pressure decrease, this
allow air to enter the thoracic cavity
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the
volume of the thoracic cavity decrease as the pressure increase, this force
air out of the thoracic cavity
|
|
6.
Air enter the alveoli through the nostril, pharynx, glottis, trachea, bronchioles
and finally alveoli
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Air
leaves the alveoli through brancholes, trachea, glottis, pharynx and finally
nostril
|