Giraffe hearts pump less blood than other mammals, to make sure oxygen reaches the top of their long necks – compromising volume for pressure.
Because of their long neck, scientists have long debated how the Giraffe’s heart is able to produce enough blood pressure to pump blood up to their lofty brains. A remarkable study published in the Journal of Experimental Biology sheds light on the inner working’s of the Giraffe’s heart. Morten Smerup and colleagues anesthetized 9 adult male giraffes, hoisted them into an upright position, and measured their cardiac output. They found that the very thick wall of the left ventricle enabled the heart to produce sufficiently high blood pressure to overcome gravity and supply oxygenated blood to the brain. But increased pressure comes with a cost – reduced output – the giraffe heart pumps a smaller quantity of high-pressure blood with each stroke in order to overcome gravity and supply blood to the brain. At least it’s pretty easy to get the blood back down to the heart again afterwards!
Want to Know More?
- Smerup et al (2015) The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output Journal of Experimental Biology
Featured image is used with permission from Curiosity Photographic.