SirDuke6 OP t1_j2a70yg wrote on December 30, 2022 at 7:34 PM

Reply to comment by nstickels in ELI5: Why does putting one foot out from under the blankets bring so much relief of heat while laying in bed? by SirDuke6

That's awesome. I had no idea how fast blood moved but that's pretty incredible.

I mean, I know how powerful it was based off of things like how far blood squirts out of an artery/vein when cut but didn't have an actual speed to comprehend it at.

iNd3xed t1_j2avjsv wrote on December 30, 2022 at 10:14 PM

Although the above comment is not wrong about the high speed of blood this is only the case close to the heart.

In smaller blood vessels, and especially in veins, blood flows much slower, as low as a couple of centimeters per second in the index finger [https://pubmed.ncbi.nlm.nih.gov/11284002/]

Not that this helps answer the original question by much, but this adds some nuance to the answer

fiendishrabbit t1_j2ay0ih wrote on December 30, 2022 at 10:31 PM

If I remember my biology right, on average it takes 45 seconds for blood to make a full round-trip. Very fast in the aorta, much slower elsewhere.

MalleableCurmudgeon t1_j2dhns2 wrote on December 31, 2022 at 1:11 PM

I served in Iraq during the ‘00’s and on particularly hot days, after patrols and convoys, we’d go to the medics for a bag of IV fluid they’d keep slightly chilled. Holy holy! The relief of cool fluid directly into the veins and feeling it move from my arm throughout my whole body was awesome!

Crepuscular_Oreo t1_j2fdd4p wrote on December 31, 2022 at 9:28 PM

>I had no idea how fast blood moved but that's pretty incredible.

The speeds of various bodily processes are interesting. I have nerve damage. I was lying on the table at the doctor's office while they were testing the speed that signals travel from one part of my body to another. Being bored while the tests were going on, I did the math and calculated that the runners in the 100-meter dash at the Olympics run faster than my nerves send signals through my body. That seemed strange to me; I always thought of nerve signals being instant. It was several years ago so I don't remember the exact numbers.