"Top of the World, Ma!"
The Giraffe has a unique circulatory system that is able to control the high blood pressure needed to pump the blood from the heart up the long neck to the brain. Thick-walled elastic arteries and valved veins in the neck help counteract the effects of gravity. Pressure in the brain is regulated by a rete mirabile, "a wonderful net" of intertwining blood vessels which also serves as a mechanism for heat tolerance.
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