Answer:

While the exact answer will be dependent on which anatomy textbook is referenced, the generally excepted answer is approximately 60,000 miles of blood vessels in the body of a child and roughly 100,000 miles in the body of an adult.

The circumference of the earth, at the equator, is approximately 25,000 miles. If all of the blood vessels of an adult were placed end to end, the blood vessels would circle the equator four times.

Most of the blood vessels in the human body are composed of microscopic capillaries. While the microscopic capillaries may be short in length, there are approximately 40 billion (40,000,000,000) of them in the human body.