What carries oxygen poor blood to the lungs from the heart?

Answer 1

Think about it logically. The lungs are the organ designed to allow transfer of oxygen from the air into the blood and CO2 from the blood back into the air. Delivering blood that already contains oxygen to this organ would therefore be a complete waste of time as more oxygen will not be able to get into the system. So it must be oxygen poor blood that goes to the lungs, where is takes up oxygen ready to go around delivering it to the rest of the organs. And indeed oxygen poor blood is the answer to your question. However things are never as simple as that are they. Only the cells of the alveoli get enough oxygen from the air irectly to survive. The bronchi nad bronchioles are too many cells thick for simple diffusion of oxygen from the air to sustain them. This means that like the rest of the body the cells in these part must reciece and oxygenated blood supply, which comes from the systemic circulation (ie not the pulmonary circulation) from the left side of he heart. The arteries that carries the oxygenated blood to these parts of the lungs are called the bronchial arteries. Their are bronchial veins that help to drain this blood, once is has been deoxygenated, back into the systemic circulation but interestingly the majority is drained by the pulmonary veins (which carry the oxygenated blood back from the alveoli). This causes a slight impurity in the oxygenated blood that is taken back to the left ventricle of the heart to be pumped around the body.

Answer 2

Pulmonary artery