If a child’s entire circulatory system—we’re talking veins, arteries, and capillaries—were laid out flat, it would stretch for more than 60,000 miles, according to the Franklin Institute. By the time we reach adulthood, our bodies have become home to approximately 100,000 miles of blood vessels. That’s just one of the You do not have permission to view the full content of this post.Log in or register now. that sound made up (but aren’t).