Q What is the circulatory system?
A The heart, the lungs and the blood vessels are part of the circulatory system. Humans have about 100,000 kilometers (62,000 miles) of blood vessels in their body. This is enough to circle the
Earth two and a half times! Blood vessels are made up of arteries, veins and capillaries.
A The heart, the lungs and the blood vessels are part of the circulatory system. Humans have about 100,000 kilometers (62,000 miles) of blood vessels in their body. This is enough to circle the
Earth two and a half times! Blood vessels are made up of arteries, veins and capillaries.
