Arteries (shown in red) carry blood from the heart to the rest of the body, while veins (shown in blue) carry blood from the body...Read More >>Arteries (shown in red) carry blood from the heart to the rest of the body, while veins (shown in blue) carry blood from the body back to the heart.Blood travels along thousands of tubes, called blood vessels. Blood vessels that take blood away from the heart are called arteries. Blood vessels that take blood towards the heart are called veins. The arteries and veins in your body are like a road network. There are “motorways” (the main blood vessels) as well as “lanes” and “tracks”, tiny vessels called capillaries that reach all the cells in the body. Altogether, your blood vessels are about 100,000 kilometres (60,000 miles) long, or more than twice the distance around the world.
Valves inside veinsVeins carry blood containing carbon dioxide and other wastes from the cells towards the heart. The larger veins have valves inside them. These are “doors” that open and close rather like canal locks. The valves ensure that blood cannot leak back.
The only place you can normally see blood in your body is on the retina at the back of your eye. This is revealed when photo is taken of you by flashlight.
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