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Old 08-20-2011
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Question changes in PaCO2 in case of exercise

Hi all:

I have a question. In case of exercise, we HYPERventilate in order to meet increased oxygen demand, so why in " FA 2011 p. 509 Respose to exercise "

it says that no change in PaCO2?? Since PACO2 is proportional to PaCO2 and PACO2 is inverse proportional to ventilation, then as we HYPERVENTILATE, we should have low PACO2 and PaCO2, right?

Please help me explain why it is no change in FA, thank you.
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Old 08-21-2011
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PACO2=CO2 production/alveolar ventilation.
So though we hyperventilate the amount of CO2 production is also increasing leading to constant to PACO2.
Hope this helps
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Old 08-21-2011
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During exercise, there is an increase in ventilatory rate (to supply body's demand for oxygen) that matches the increase in O2 consumption and CO2 production by the body. The stimulus for increased ventilation rate is not completely understood. It is still a mystery how the ventilation can be altered so precisely to meet the increase demand when these parameters seem to remain constant in the blood. Maybe chemoreceptors (when PaCO2 elevates) or mechanoreceptors in joints have something to do with it.

Hope this also helps.
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Physiology-, Respiratory-

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