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drsmita_s
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Physiology
mock test :VA/Q
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11.22.05 (3 years ago)
#1
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All the following are true of VA and Q in the lungs of a healthy, standing individual except :
One answer only.
a) Q is greater at the base than at the apex
b) VA is greater at the apex than at the base
c) VA / Q is greater at the apex than at the base
d) Differences in VA / Q from apex to base are less during exercise
e) The VA / Q distribution causes higher PAO2 at the apex than at the base
i feel the answer given is wrong. anyone with a similar opinion?
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guest
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11.23.05 (3 years ago)
#2
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(a) is not right!
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gandalf
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11.24.05 (3 years ago)
#3
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why chand?? a) is right....b) is wrong...
It is given in ganong that, ventilation and perfusion declines in alinear fashion frm base to apex...but the ratio is higher in the apex...thats why TB is common in upper lobes....
will give u the ref soon......
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gandalf
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11.24.05 (3 years ago)
#4
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Ventilation/Perfusion Ratios
The ratio of pulmonary ventilation to pulmonary blood flow for the whole lung at rest is about 0.8 (4.2 L/min ventilation divided by 5.5 L/min blood flow). However, there are relatively marked differences in this ventilation/perfusion ratio in various parts of the normal lung as a result of the effect of gravity, and local changes in the ventilation/perfusion ratio are common in disease. If the ventilation to an alveolus is reduced relative to its perfusion, the PO2 in the alveolus falls because less O2 is delivered to it and the PCO2 rises because less CO2 is expired. Conversely, if perfusion is reduced relative to ventilation, the PCO2 falls because less CO2 is delivered and the PO2 rises because less O2 enters the blood. These effects are summarized in Figure 34-21.
As noted above, ventilation, as well as perfusion, in the upright position declines in a linear fashion from the bases to the apices of the lungs. However, the ventilation/perfusion ratios are high in the upper portions of the lungs. It is said that the high ventilation/perfusion ratios at the apices account for the predilection of tuberculosis for this area because the relatively high alveolar PO2 that results provides a favorable environment for the growth of the tuberculosis bacteria.
(GANONG)
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DRATKINS
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11.24.05 (3 years ago)
#5
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ventillation is higher at apex--rt
perfusion is higher at base--rt
v/p ratio is highr at apex--rt
ion,exercise there is increase in perfusion % ventillation both..bt variation is less-d is rt
it's e wich is the ans????
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guest
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11.24.05 (3 years ago)
#6
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You are right gandalf, I was wrong! Sorry for that!
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candy
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11.24.05 (3 years ago)
#7
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candy
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11.24.05 (3 years ago)
#8
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candy
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11.24.05 (3 years ago)
#9
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gandalf
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11.24.05 (3 years ago)
#10
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Hey candy!!! that was a good improvisation!!!!!!!!!
and I thought u were busy with ur patients?!!!!
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