Our heart acts as a pump to circulate the blood to different parts of our body. Blood vessels carry oxygen poor blood to heart, from where it is sent to the lungs to get fresh oxygen supply. Oxygen rich blood is sent back to heart and from there it is supplied to the rest of the body. There are two types of blood vessels in our body: veins and arteries. It is the veins that carry blood to the heart. There are two major veins in our body: pulmonary veins and vena cavae. The former carries oxygen rich blood from our lungs to the heart, while the latter (including both superior and inferior vena cave) carries oxygen poor blood from the body back to the heart.
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