The heart pumps blood throughout the body, including upwards against gravity. The heart is a powerful muscle that contracts and relaxes to pump blood through the body's network of blood vessels. The contraction of the heart's left ventricle creates pressure that pushes blood out of the heart and into the aorta, the body's largest artery. The aorta carries blood to the rest of the body, including the head and arms. The blood vessels in the head and arms have valves that prevent blood from flowing backwards, so blood can only flow upwards.

In addition to the heart's pumping action, the body also has a system of valves in the veins that help to keep blood flowing upwards. These valves are located in the larger veins and they open and close to allow blood to flow towards the heart and prevent it from flowing backwards. The combination of the heart's pumping action and the valves in the veins ensures that blood is able to travel upwards against gravity.