AAMC 6 Question 51

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ronaldo23

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In a healthy person standing at rest, a comparison of arterial blood pressure measured in the arm with that measured in the leg shows that the pressure in the leg is:

A. lower because blood flow rate is less.
B. lower because viscous flow resistance causes pressure loss
C. the same because viscous pressure loss precisely compensates
the hydrostatic pressure increase
D. greater, because the column of blood between the arm and leg has a
hydrostatic pressure.

The answer is D, and the explanation says to use the equation F=pgV

I reasoned D, but using Bernoulli's equation instead whcih states:
P + pgh + 1/2pv^2= constant. Because pgh is greater for an arm, the pressure must be less compared with the leg. Is this logic correct? I just want to make sure i didn't arrive at the right answer w/ wrong reasoning...
 
In a healthy person standing at rest, a comparison of arterial blood pressure measured in the arm with that measured in the leg shows that the pressure in the leg is:

A. lower because blood flow rate is less.
B. lower because viscous flow resistance causes pressure loss
C. the same because viscous pressure loss precisely compensates
the hydrostatic pressure increase
D. greater, because the column of blood between the arm and leg has a
hydrostatic pressure.

The answer is D, and the explanation says to use the equation F=pgV

I reasoned D, but using Bernoulli's equation instead whcih states:
P + pgh + 1/2pv^2= constant. Because pgh is greater for an arm, the pressure must be less compared with the leg. Is this logic correct? I just want to make sure i didn't arrive at the right answer w/ wrong reasoning...

F=pgV is the buoyant force which has nothing to do with the problem. I don't know where that came from.

Your reasoning is correct. You can also use the "depth" equation which is another form of Bernoulli's equation, and you would get to the same answer.
 
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