There are long tubes inside our bodies that carry blood within them. These tubes are also called blood vessels. There is a huge network of blood vessels in our bodies. If we laid all-out blood vessels down, from end to end they will be about 60,000 miles long for a child and about 100,000 miles for an adult!
The blood vessels carrying fresh blood from the heart to the body are called Arteries. (Also called red blood vessels)
The blood vessels carrying the impure blood from the body to the heart are called Veins. (Also called blue blood vessels.)