2016-11-15
Seminar questions respiratory physiology
(15/11-16)
• During the Olympic games in Mexico City (2,240 m
above sea level) in 1968, the world record holder at
10,000 m collapsed with 500 m left of the race and
finished in 6th place. What happens to the body at high
altitude and how does the body adapt?
• How are ventilation and perfusion (blood flow)
matched in the lung?
• Hyperventilation:
– Why can a person faint when hyperventilating?
– Why is it bad to hyperventilate before swimming under
water?
Environmental Conditions
at Altitude
• Sea level (<500 m): no effects
• Low altitude (500-2,000 m)
– No effects on well-being
– Performance may be , restored by acclimation
• Moderate altitude (2,000-3,000 m)
– Effects on well-being in unacclimated people
– Performance and aerobic capacity
– Performance may or may not be restored by acclimation
• High altitude (3,000-5,500 m)
– Acute mountain sickness
– Performance , not restored by acclimation
• Extreme high altitude (>5,500 m)
– Severe hypoxic effects
– Highest settlements: 5,200 to 5,800 m
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Environmental Conditions
at Altitude (continued)
• High altitude (3,000-5,500 m)
– Acute mountain sickness
– Performance , not restored by acclimation
• Extreme high altitude (>5,500 m)
– Severe hypoxic effects
– Highest settlements: 5,200 to 5,800 m
• For our purposes, altitude = >1,500 m
– Few (if any) physiological effects <1,500 m
(continued)
Environmental Conditions
at Altitude
• Pb at sea level exerted by a 24 mi tall air column
– Sea level Pb: 760 mmHg
– Mt. Everest Pb: 250 mmHg
• Pb varies, air composition does not
–
–
–
–
20.93% O2, 0.03% CO2, 79.04% N2
PO2 always = 20.93% of Pb
159 mmHg at sea level, 52 mmHg on Mt. Everest
Air PO2 affects PO2 in lungs, blood, tissues
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Hypoxic Vasoconstriction
Rhoades and Pflanzer.
Human physiology. 4th
ed. Pacific Grove,
Thomson, 2003
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