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Kom i tanke om udtrykket “girafhjerte” …

Faktisk er det ordet “Girafsprog”, som jeg burde være kommet i tanke om – men tanken opstod i forbindelse med en bemærkning om en teenager, der skød i vejret og ikke behøvede at blive højere. Udtrykket girafsprog betegner sprog hvor man ikke kritiserer, men prøver at forstå og løse interessekonflikter, og ordet er valgt af Marshal Rosenberg (konfliktløser) fordi giraffen et stort hjerte. (Det er så ikke helt faktuelt, blåhvalens hjerte er større.)


Hovedet er 2½ – 3 meter over hjertet. Intet andet dyr har så stor højdeforskel!

This long stretch of circulatory real estate is covered by the efforts of a relatively small but powerful heart. “The giraffe’s heart must pump hard enough to overcome the huge hydrostatic pressure generated by the tall column of blood in its neck…,” wrote researcher Qiong Zhang, at the time at CalTech, in his published paper Hypertension and Counter-Hypertension Mechanisms in Giraffes. Harder pumping to get all that blood so far uphill results in very high blood pressures.

In fact, an adult giraffe’s blood pressure can reach 300/180 millimeters, according to zoologists. That’s roughly twice that of an adult human. But that’s only near their hearts. In their heads, a giraffe’s blood pressure remains about equal to a human’s.

And they maintain that lower pressure in their heads despite whether they are chomping leaves from the limbs of tall trees or sipping water at ground level. The reason? A giraffe’s large neck veins contain a complex system of valves that stop the blood from flowing backward and pooling when it dips its head, which can be a full 20 feet differential from upright in a full-grown giraffe. Humans would pass out if they tried that trick.

Written by Donald

Monday, January 25, 2021 at 1:02 GMT+0000

Posted in Videnskab

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