combined physics and bio concepts

[rebel1]

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I understand the concepts in physics and bio well but once they are combined in a problem for some stupid reason i get messed up. Here is one sample problem that someone has posted but i didn;t understand why and how they got the answer.



Q: 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
Alternative method: use P + pgh + 1/2pv^2= constant. Because pgh is greater for an arm, the pressure must be less compared with the leg.



Please post more combined concept problems in this thread. i really want to overcome my fear.

 

[loveoforganic]

Problems on gel electrophoresis would potentially be worth looking into.

 

[golgiapparatus88]

Fluids like to move from high pressure to low pressure. In the case of a standing person at rest, the blood needs to get from somewhere near the ground (foot/leg) back to the top.

May not be the most scientific reason but I think it's a good way to look at it!

 

[rebel1]

Thank you loveoforganic

 

[rebel1]

Thanks dlouis

 

[RogueUnicorn]

i would imagine they could combine circuits & membranes in a passage. lots of physiology in general combines physics with bio

edit: i don't think this would really happen in a real MCAT though, since physics is PS and bio is BS. if you see a bio passage in the PS you can safely assume it has nothing to do with bio.