Giraffes are just as astonishing on the inside as they are to look at. Standing up to 19 feet tall, they require enormou…

Giraffes are just as astonishing on the inside as they are to look at. Standing up to 19 feet tall, they require enormously high blood pressure to pump blood up to the head, yet they suffer few, if any, of the consequences that people with high blood pressure would.

Giraffes have sky-high blood pressure because of their sky-high heads that, in adults, rise about six meters above the ground — a long, long way for a heart to pump blood against gravity. To have a blood pressure of 110/70 at the brain — about normal for a large mammal — giraffes need a blood pressure at the heart of about 220/180. It doesn’t faze the giraffes, but a pressure like that would cause all sorts of problems for people, from heart failure to kidney failure to swollen ankles and legs.

Giraffes have solved a problem with high blood pressure. Their solutions, only partly understood by scientists so far, involve pressurized organs, altered heart rhythms, blood storage — and the biological equivalent of support stockings.

@science