Why does a giraffe not faint with low blood pressure even if she moves her head?

The giraffe, a representative of long-necked animals, has various physical functions built to send blood to the brain. Several studies have revealed how giraffes maintain blood pressure in the body.

The Cardiovascular Secrets of Giraffes | Science | Smithsonian Magazine


The giraffe's head can reach up to about 6 meters above the ground if it is an adult. In order to maintain the blood pressure of the giraffe's brain at 110/70, which is the normal blood pressure of large mammals, it is necessary to keep the blood pressure of the heart at 220/180. With such blood pressure, giraffes can develop arrhythmias and heart failure.

A study by evolutionary biologist Barbara Horowitz and colleagues found that Kirin's heart did not show symptoms such as sclerosis or fibrosis , even though the left ventricle was thickened to maintain high blood pressure. Is known. Another study also found that giraffes carry five specific genes for fibrosis that are predicted to alter protein function. Horowitz et al. Speculate that 'the rhythm of the giraffe's heart beating is different from that of other mammals, so the cycle of blood filling the ventricles may be different.'

One of the symptoms of high blood pressure that occurs in humans is swelling of the legs, which is caused by the push of water from blood vessels into tissues. Biologist Christian Arkuya's research shows that the reason why giraffe's legs do not swell is that giraffe has a dense connective tissue that compresses the tissue and prevents fluid from accumulating. I will. Arkuya also speculates that 'giraffes use arteries near the knees to lower blood pressure in the lower limbs.'

Also, when a giraffe lowers her head when drinking water and raises her head again, she will not faint due to a decrease in blood pressure. The reason for this is that 'more than 1 liter of blood is stored in a mass of capillaries called a wonder net, and the amount of blood inflow and outflow to the brain is regulated by utilizing a valve to prevent regurgitation.'

Biologists such as Horowitz believe that by studying the structure of the giraffe's body, it may be possible to derive treatments for human hypertension and the like.

in Science,   Creature, Posted by log1p_kr