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Two main types of blood vessels work together to carry blood through your body: arteries and veins.

Arteries are thick vessels that carry blood to all of the cells in your body after it has picked up oxygen from the lungs.

Veins are thinner. They carry blood back from your cells to your heart. From here the blood is pumped to the lungs to pick up more oxygen.

Then, your blood returns to your heart and is pumped out into your body to start the cycle again.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.