what transfers waste-filled blood from tissues into the pulmonary circulation. aortas, arterioles, or capillaries?

I believe the correct answer is the pulmonary artery.

The pulmonary circulation starts from the pulmonary artery that receives blood from the right ventricle. The artery then take the blood to the lungs where oxygen is added and carbon dioxide is removed then taken back to the left atrium via the pulmonary vein, into the left ventricle and back to the tissues via the aorta.

Circulation is divided into systemic circulation and pulmonary circulation. Pulmonary circulation supplies the blood that has waste and carbon dioxide to the lungs where oxygen is added after carbon dioxide is removed. The blood from tissues is picked up by capillary bed in the superior region of the body that includes the neck, chest and head and supplied to the superior vena cava and the lower regions including the limbs, pelvic region and the abdomen are picked up by capillary beds and supplied to the inferior vena cava. Both these veins take the blood to the right atrium of the heart that then passes the blood to the right ventricles and the right ventricle pumps the blood to the pulmonary artery that is the only artery in the body that carries de-oxygenated blood. The pulmonary artery carries the blood and distributes it to capillaries in the lung tissues that then allow the diffusion of carbon dioxide into the alveoli of the lungs and then out of the body while oxygen is dissolved and diffused across the alveoli membrane into the waiting capillaries. The diffused blood with oxygen in the other bed of capillaries feeds the pulmonary vein. This vein takes the oxygenated blood away from the lungs into the left atrium that then pumps the blood into the left ventricle which supplies the whole of the body with oxygenated blood via the aorta that divides into several branches that supplies supply capillaries which in turn supply the tissues that need oxygenated blood.

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