A video taken on the 28th of December 2015. Giraffes have the largest heart of all land mammals and it can weigh up to 10kg which necessitates maintaining a blood pressure two times higher than those of humans. Blood pools in an area just below the brain called the blood sponge which consists of a huge amount of tiny capillaries which helps to release this pressure. Spongelike valves below the head would slowly release blood to the head when lowered to drink and also restricts the flow when the head is raised again. Blood vessels in the lower legs are also under tremendous pressure from the weight of the fluid pressing down on them. Their walls are thick and can constrict mimicking the workings of the G-suits that fighter pilots wear.
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