If you roll your hand into a fist, that's about the size of your heart. That is, if you are a child. If you are an adult. It's about the size of your two fists. Your heart grows at the same rate as your body, so at any point of your development your fists should correlate to the size of your heart.

The aorta, the largest artery in the body, is almost the diameter of a garden hose. Capillaries, on the other hand, are so small that it takes ten of them to equal the thickness of a human hair.

Your body has about six quarts of blood. These six quarts circulate through the body three times every minute. In one day, the blood travels a total of 12,000 miles — that's the equivalent of travelling from Dockyard to St. David's Point 545 times.