v = Q/A where
v = velocity (cm/s) Q = blood flow (ml/s) A = cross sectional area (cm2)
So the greater the cros sectional area, the lower the velocity, assuming that the cardiac output is a constant for a individual. But i dont understand the formula content wise, why do you get the velocity by dividing Q by A? I do understand that the units are correct, and you get cm/s as final unit. Can anyone explain this, perhaps graphically?
In the capillaries the A must be extremely low, yet why is the velocity so small? My book says that you have to add all capillaries up, but you cant do that, since you would get the velocity of an extremely big pipe, which isnt that of a capillary?
Thanks in advance for answering.