macTT
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A healthy 50 year old male takes a 45 min. ride in a cable car up to a ski resort (high elevation) Which of the following points best describe the physiology after 30 min arrival to the resort?
HAving a hard time choosing btwn D or C. Reason not choosing C is because bicarb concentration seems a bit high. Leaning towards D. Need to help if possible. Thx
JACK
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| bangledoc
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D is the answer
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| johnnyu041
Forum Junior
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can u explain why its D?
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| Ancylostoma
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first you have to understand that this is an acute situation, and go with one cardinal rule. Metablic acid/base problems can be compensated immediately via respiration, second, respiratory acid/base problems are compensated via the kidney and at the very least takes days to weeks to complete it compensation. The air in mountain climates gets thinner and thus we have a low po2. Normally the drive for respiration is the change in co2 . Increase in co2 means we will increase ventialtion. Decrease does the opposite. This control is provided by the central chemorecptor in the medulla. Now the preipheral chemo receptors in the carotid body detect po2, but under normal conditions these do not provide the drive for respiration. Extremly low levels of po2, switch the drive from cnetral chemo receptor to peripheral one. making o2 the only drive for respiration.
Summary: repiratory conditions cause low po2, this causes the initiation of peripheral chemoreceptors that cause hyper ventilation. Hyperventilation decreases the amount of co2 , the curve moves to d. Hco3 remains the same because this is an acute situation and renal compensation takes time. Thus the point is D . Remember the normal position is to the left of D with the same hco3 but pco2 of 40.
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| macTT
Forum Senior
Topics: 32
Posts: 86
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Great explanation,
Thanks guys....
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