Thursday, March 15, 2007

Laplap slurpslurp glubglub lub dub

So there was this really tall guy who bent down to drink from the water fountain in the hall just now. It struck me in a funny way and reminded me of something...

Actually, the giraffe's circulatory system is one of the
wonders of Creation intelligent design evolution whatever. Because its head (and the brain within) is so far above its heart, the giraffe must maintain a blood pressure much higher than other mammals (about 240/160), and has a very large (~24 lbs) and powerful heart to accomplish this.

Because of their hard-working hearts and high blood pressure, giraffes are very susceptible to heart attacks when frightened or experiencing prolonged exertion, so when catching a giraffe, be sure not to chase it too long. Zoo-keepers also blindfold giraffes sometimes to avoid stressing them too much.

And finally, a mystery solved:

"...researchers explain that most other mammals, including humans, elephants, and mice, have similar blood pressures, because all of them have a similarly proportional distance between the head and the heart. Because of its long neck, a giraffe's blood pressure is twice as high as a human's blood pressure, yet it doesn't suffer from blood pressure-related diseases or dizziness -- despite an extraordinary rush of blood from the head in the two seconds it takes to lift its head 15 feet from a drinking position to a standing one.

The model reveals nature's evolutionary solution, which prevents giraffes from becoming dizzy in their predator-studded environment. A muscular cuff, which acts much like the device used to constrict a human arm during blood-pressure tests, surrounds the jugular vein. It regulates blood flow while the giraffe lifts its head, until the animal's powerful heart can pump blood up its long neck to the brain."

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