blood

[niki piki]

how long does it take for blood to make one complete circuit of the human body?

[bernardo]

About 10 or 15 minutes (I think)

[silly moo]

When injecting radio-opaque dye for an IVP, the dye shows in the kidneys within less than 1 minute!!!
Not answering your question I know but shows that blood moves very quickly

[jake-the-peg]

I think it's going to be highly dependant on factors like arterial condition and especially heart rate

[NetSquirrel]

You would not expect all blood cells leaving the heart at a particular time to make the same "round trip" back to the heart.  As it flows the blood is forced to split up and travel down thousands of vessels, some linking back to the heart fairly directly, and some leading right to the body's extremities and back again.  Clearly, then, there is going to be a wide range of possible values for any given blood cell's circulation time.  Even blood cells that are adjacent to each other when they leave the heart and travel along the exact same arteries and veins could still arrive back at the heart at quite different times.  This "smearing" effect suggests that 60 seconds might be an approximate minimum time for a complete heart > heart cycle, while 15 minutes can be considered roughly maximum.  In reality you would of course get an average circulation time which would correspond to the time when the blood that has left the heart is re-entering it at its maximum rate.  (Normal distribution.)

[Kingaroo]

Well said, NETSQUIRREL. No single blood cell leaves the heart, runs down the arms through each finger, back up to travel down the torso to each leg in turn, and so on, finally returning to the heart for another "circuit."