Question

i am confused! i have learned that artery always carries oxygen rich blood and vein carries CO2 rich blood. but pulmonary artery carries co2 rich blood and pulmonary vein carries o2 rich blood then why the pulmonary vein is not artery. and pulmonary artery is not a vein.

Answer 1

no need to get confused, the work of pulmonatory artery and vein is inverse

Answer 2

it is not a concept of confusion . pulmonary means opposite . pulmonary vein always carry o2 blood and pulmonary artery  always carry co2 blood . it is a part of heart and plays a major role so it is give a different name which differentiate between other normal veins and artery.