AP BIOLOGY

Detailed explanation-1: -The oxygenated blood is brought back to the heart by the pulmonary veins which enter the left atrium. From the left atrium blood flows into the left ventricle. The left ventricle pumps the blood to the aorta which will distribute the oxygenated blood to all parts of the body.

Detailed explanation-2: -Oxygen-rich blood flows from the lungs back into the left atrium (LA), or the left upper chamber of the heart, through four pulmonary veins.

Detailed explanation-3: -Explanation of the correct answer: The pulmonary vein is the largest vein. It plays an essential role by receiving blood that has been oxygenated in the alveoli and returning it to the left atrium. This vein transfer oxygenated blood from the lungs to the heart.

Detailed explanation-4: -Pulmonary artery carries oxygenated blood from lungs to the heart.

Detailed explanation-5: -Normally, each pulmonary vein connects directly with your left atrium. In that case, there are four ostia (openings) in your left atrium, one for each of your pulmonary veins. Oxygen-rich blood travels through these openings and into your left atrium.