circulation is very important process in human life.it had done by the heart .main one involved in this are veins,artery. in them pulmonary artery and pulmonary vein.heart pumps blood to lungs for oxygenation and lungs to body parts.this is known as circulation
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circulation is very important process in human life.it had done by the heart .main one involved in this are veins,artery. in them pulmonary artery and pulmonary vein.heart pumps blood to lungs for oxygenation and lungs to body parts.this is known as circulation