dr_kh
Forum Newbie
Topics: 11
Posts: 19
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In a healthy subject , in which situation is the pO2 of blood leaving the pulmonary capillary lower pO2 in alveolus served by that capillary/
A )While breathing a low O2 gas mixture
B)While performing an execise in which cardiac output doubles
C)at base of lungs
D)at apex of lungs where where ventilation exceeds perfusion
E) none of the above
Can someone tell the correct answer and explain it
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| Luckyall
Forum Guru
Topics: 11
Posts: 593
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in which situation is the pO2 of blood leaving the pulmonary capillary lower pO2 in alveolus served by that capillary/
Im assuming you ask where is the PO2 of blood leaving capill. lower THEN < PO2 of Alveoli serving that capillary , i think is E
lets try to explain each option BASE is underventilated, but PAO2 <100mmHg and PO2 is also<100 mm /hg----> no diffussion defect
in exercise---->there is a lage incr in CO---> incr volume pumped into pulm circuit--->incr in pulm press.but due to passive, compliant nature of pulm circ. the response to this incr. in Pressures is a VASODILation---> therefore during exercise is only a slight incr on pulm press
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| keepgoing
Forum Guru
Topics: 63
Posts: 1,676
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oops dint get what is being asked here...?sorry can u plzz complete the sentance...
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| virgola82
Forum Guru
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I think the point tested here is diffusion vs perfusion limited gas exchange. I am not very good in this actually, but if I remember well oxigen is perfusion limited (ie capillary pO2 equilibrates w alveolar before exiting alveolar capillary bed, right?) If that's the case maybe A is the answer because if the gradient reduces than diffusion slowes down and maybe the two partial pressures are not yet equilibrated at the end of capillary bed.
Don't know if this is right, let me know what you think
Edited by virgola82 on 05/02/07 - 10:48 AM
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