Your blood vessels could circle Earth twice

An adult human body contains approximately 60,000 to 100,000 miles of blood vessels. If you tied them end-to-end, they could circle the entire globe more than two times.

The vast majority of this length doesn't come from thick arteries or veins, but from capillaries. These are the microscopic vessels so thin that red blood cells have to march through them in single file, often squeezing and deforming just to fit.

Capillaries are everywhere. They are so densely packed into your tissues that almost no cell in your body is further than the width of a human hair away from a blood supply. Your lungs alone contain about 1,500 miles of these tiny tubes to facilitate gas exchange.

This massive network is controlled by a heart that is only about the size of a clenched fist. This small muscle pumps roughly 2,000 gallons of blood through that 60,000-mile circuit every single day.

Even more incredible is the speed of the transit. Despite the epic length of the vessel network, it takes a single drop of blood only about 60 seconds to complete a full circuit from the heart, to the furthest toe, and back again.