Question

_________the lungs transfer oxygen from the air to the blood it is then returned to the the heart by via the pulmonary veins

Answer 1

I believe the answer is Pulmonary vein.
Pulmonary vein receives the oxygenated blood through the alveoli of the lung and returns the oxygenated blood to the left atrium of the Heart.
From this, the oxygenated blood would be pumped all over our body to support our organ system.

Answer 2

Answer:

Pulmonary artery the lungs transfer oxygen from the air to the blood it is then returned to the the heart by via the pulmonary veins

Explanation:

The pulmonary artery is a huge artery arising from the preferred covering of the right ventricle and transporting deoxygenated blood from the heart to the lungs. The pulmonary vein is the difference to the practice that veins carry oxygenated blood from the heart toward different portions of the body.

Oxygen and carbon dioxide moves to and of little air cysts in the lungs, by the walls of the capillaries, toward one blood. Blood moves the heart by the pulmonic lid, into the pulmonary vein and to particular lungs.