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kalod9 t1_j42apgu wrote

Reply to comment by NimdokBennyandAM in How do giraffes breathe? by NimishApte

I would imagine the main reason for their higher blood pressure is so blood is able to reach their heads, you need roughly 23mmHg per foot in height.

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Vazmanian_Devil t1_j42gbb2 wrote

yup, iirc, their skin is super tight around their legs to help get that blood to easily shoot up the neck.

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zz_z t1_j43q7ni wrote

Don’t fighter pilots or astronauts do the same thing with their suits to resist passing out from g forces?

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Myownprivategleeclub t1_j43qpm1 wrote

Yes. They wear pneumatic over trousers which compress the legs in high g manoeuvres to keep the blood in the upper body and brain. Pilots are also trained to clench the core and hold their breath to keep pressure up.

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zz_z t1_j44059o wrote

What an incredible wealth of knowledge we all possess. I thought it was like tight stockings or something.

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Fuegodeth t1_j44fgfu wrote

Fun fact: The Blue Angels don't wear G-suits because they maneuver so closely and don't want the suits to impact their controls during displays.

From their FAQ: https://www.blueangels.navy.mil/faq/

G-suits are designed with air bladders (pockets) that inflate and deflate to keep a pilot's blood from pooling in the pilots' legs while executing sharp, unpredicted combat maneuvers. Unlike combat flying, the Blue Angels demonstration pilots know the maneuvers they will fly prior to execution, so each pilot knows when one will be experiencing heavy gravitational forces. Anticipating the changes in gravitational forces allows the Blue Angels demonstration pilots to combat G-forces with muscle contractions. Additionally, G-suits would detrimentally impact flight safety.The Boeing F/A-18's control stick is mounted between the pilot's legs. The Blue Angels have a spring tensioned with 40 pounds of pressure installed on the control stick that gives the pilot a "false feel." This allows the pilot minimal room for un-commanded movement. The pilots rest their right arms on their thighs for support and stability while flying. Therefore, inflating and deflating air bladders in a G-suit would interrupt this support and stability, causing un-commanded aircraft movement.

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_CMDR_ t1_j44v6dq wrote

I use that core trick if I get lightheaded from standing up too fast and it works 100% of the time to make it stop quickly.

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napincoming321zzz t1_j45dx90 wrote

I've dealt with (annoying, but not dangerous) low blood pressure my whole life, and never once has a medical professional ever mentioned flexing my core as a way to combat occasional dizziness. I'm weirdly excited to try it out!

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glasser999 t1_j452swj wrote

Yes, and they also flex their legs and core to keep blood flow to the brain.

You can do the same thing if you ever feel like you're going to pass out.

When you start getting tunnel vision, squeeze that core. It'll either resolve it, or keep you conscious long enough to find a place to sit.

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pow3llmorgan t1_j45xly7 wrote

They also have a pressure regulator on their carotid artery (jugular?), which allows them to lower their head to drink.

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Hagenaar t1_j435x6j wrote

So, if you measured a giraffe's BP at the head (while standing tall) would it be similar to a human's? And do they suffer a major headrush when going from ground grazing to treetops?

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froggo921 t1_j440rl7 wrote

Apparently, a giraffes BP is 280/180mmHg

Regarding the headrush, they don't

Edit:

Giraffe's have basically a vascular sponge in their brain, which dampens BP spikes when moving the head. Also, their arteries have valves as well.

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Hagenaar t1_j445ck8 wrote

Right. But where are we measuring that bp? I'd assume body as there's no need to have that much pressure at the brain.

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froggo921 t1_j445nkn wrote

At heart level as always. At head level it's apparently at 75mmHg while a humans at headlevel being 60mmHg

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kickedonce t1_j44b0l5 wrote

I also have a sponge in my brain. But that's another story. I dampen tictock videos and ignore all of them.

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Halictus t1_j45nukt wrote

23mmHg per foot is equal to 0.10133 bar/meter.

Imperial units are wonky, and mixing them with outdated half-metric converted units makes my head hurt.

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Chemputer t1_j44mhbz wrote

That's 0.44 psi per foot, which at 6ft is 2.64 psi, which doesn't sound like a lot, but considering it's going through blood vessels, that's absolutely insane.

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dustofdeath t1_j45bmb2 wrote

Their neck arteries got many valves to help with gravity, back flow, pooling when they lower the head.

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surSEXECEN t1_j46s0wz wrote

I was told this by a Giraffe zookeeper once - also, they have the same number of neck ones as a human. Wild!

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ElJamoquio t1_j467s8a wrote

>I would imagine the main reason for their higher blood pressure is so blood is able to reach their heads, you need roughly 23mmHg per foot in height.

It's a closed loop system, so as long as it's primed you don't need much pressure to pump it from an engineering point of view, as long as you replace the blood vessels with non-compliant tubes.

Just throw a 12v centrifugal pump on there and you should be OK.

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