Somebody please help!?
Can somebody please explain why the vein has lower blood pressure than the artery or capillaries using physics? Hint: Use Bernoulli principle, and pressure formula possibly? Just give an good argument. Thanks.
P.S I know the mechanism of the heart pretty well, but I need physics to make a point.
Tagged with: bernoulli principle • heart • lower blood pressure • physics
Filed under: how to lower blood pressure
Dude,
I have no idea what the difference is between a vein and a artery, but I know plumbing.
When you look at the flow of a liquid in a system, the pressure gets lower and lower as the liquid moves along. This is because it is losing some of its energy to friction, and since the flow rate can’t change, it loses pressure.
You can add energy, hence pressure, to a system by using a PUMP. That is what the heart is, right, a pump? It adds pressure to the system at that point to make the entire system work. This is why the thingies after the heart have higher pressure than the thingies before the heart.
So, you can see that the maximum pressure in the system would occur right after the heart, where there has been no friction losses yet. And the lowest pressure would be right before the heart.
Now, as far as Bernoulli goes, he was talking about the dynamic pressure of a fluid WITHIN a pipe. So you could apply his principle to a single vein thingy: If the there is a certain flow rate in the vein and then the vein gets smaller, then the velocity must increase to keep the same flow rate. This increased velocity causes the pressure to drop in that section of the vein.
http://www.engineeringtoolbox.com/energy-hydraulic-grade-line-d_613.html
Not sure what the "Pressure Formula" is?
Good Luck