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| • |
Reduced PIO2 reduces pressure of O2
in blood: PaO2
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| • |
Brain
triggers respiratory muscles to bring greater volume
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of
air into lungs with each breath
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| • |
Hyperventilation-
increase volume of air inspired per
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minute
offsets decrease in air density
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| • |
# O2 molecules taken into lungs per minute is nearly same
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as at
sea level
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| • |
However, while quantity of O2 available in lungs remains
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unchanged,
PaO2 reduced as elevation increases
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| • |
Reduced PaO2 haemoglobin binds less O2; less
saturation
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of O2
in blood; reduces O2 in blood
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