A single blood cell completes a full circuit of the body in about a minute.

The human circulatory system moves blood in a continuous loop. A red blood cell leaving the heart passes through arteries, capillaries and veins and returns in a time usually estimated at 20 to 60 seconds, depending on the route it takes and how active the body is.

Over its lifespan of about four months, a single red blood cell makes this journey hundreds of thousands of times before being broken down and replaced.