Submitted by Hopeful_Anything_257 t3_z5dqje in explainlikeimfive
For humans this can be deadly id done for long periods of time, however bats seem to be doing just fine doing it their whole lifes? How does this work?
Comments
AyaElCegjar t1_ixvkp7z wrote
a good answer to an interesting question. Fine Eli5 experiences like that are hard to come by these days
-domi- t1_ixvobwz wrote
The hydrostatic pressure differential is based on the height of the column. For something as short as a bat, the contribution of hydrostatic pressure to their blood pressure isn't very significant. I.e. whatever musculature is required to keep their circulation tracking appropriately is likely enough to compensate for the hydrostatic differential.
I_summon_poop t1_ixvqa88 wrote
Giraffes have a special circulatory in their necks to combat this because their blood pressure is so high they would blow their own brains out if they bent down to the ground and didn't have it
aleqqqs t1_ixvsle6 wrote
How long can Elephants hang upside down?
germanfinder t1_ixvyxdn wrote
My head feels like it’s ready to explode after 3 seconds being upside down I don’t know how you mfers do it for minutes
haydenjaney t1_ixvyyrg wrote
Ask Manny's daughter. She thought she was a possum. She hung all night long lol
shteepadatea t1_ixwci4o wrote
It's not deadly for humans. Gravity doesn't stop your heart from pumping blood throughout your body. By that same logic your feet would always be pooling with blood when you're standing. At most you'll get headache from hanging upside-down for long periods of time.
stanitor t1_ixwgn0s wrote
ok so all of these answers talking about gravity having less influence on bats are ignoring physics and how the actual physiology of how blood flow works. Acceleration down from gravity is the same regardless of mass, so that doesn't matter. And it is only venous blood that pools lower down. As long as that blood can get back to the heart, blood pressure and blood flow will be maintained. just like humans, bats will have things like one way valves that will make sure blood in their veins only goes towards the heart and not pooling in their head.
nedrith t1_ixwpod1 wrote
Actually it is! https://science.howstuffworks.com/innovation/science-questions/hang-upside-down-how-long-safe-deadly.htm.
We evolved to stop things like blood pooling in our feet.
Granted you'd have to be upside down for a really long period of time to die from it, but bad things can happen in shorter periods of time.
shteepadatea t1_ixxg6tu wrote
Oh interesting, I stand corrected!
Hopeful_Anything_257 OP t1_ixyt7hj wrote
This was too complicated for me to understand, explain like I'm two!
-domi- t1_ixzjbe7 wrote
A 6' human will have something like 2.5 psi more blood pressure at their feet when standing, compared with their head. That's not a lot of pressure, but their blood vessels still need to squeeze a little more when standing to have the same circulation as when laying down. A bat will have less than 0.2 psi of difference upright or laying down (or upside down vs laying down). That's probably not really significant enough to require additional adaptation.
VulcanVisions t1_iy1vpq4 wrote
The walls of human blood vessels are twice as thick in the lower half of our body, to account for gravity and the fact we live standing upright.
Bats do not have this because they have evolved to vary their body position much more than humans have.
DrCortx t1_ixvfshe wrote
Bats are a lot smaller than us and have a lot less blood in their bodies, so gravity has a much smaller influence on their circulatory systems than it does for us. Similar to how we can hang upside down for a lot longer than an elephant would be able to.