How far can veins stretch?
The human circulatory system consists of arteries, veins, and capillaries.
They can stretch up to 160 000 km when laid end to end.
This is enough to stretch four times around the Earth's circumference (40 000 km).
Most of the blood vessels in the human body are capillaries.
They are short but there are billions of them.
Thus, even though they are small, they are so numerous they make up most the body's 160 000 km of blood vessels.