The pulmonary vein is the only vein in the body that carries oxygenated blood. This vein carries oxygenated blood from the lungs to the left atrium where it travels through the left ventricle and then the aorta, and is distributed to the rest of the body.
The saphenous veins, femoral veins, and popliteal veins are all veins of the lower extremity that return deoxygenated blood to the right side of the heart.
Learning Point: Veins are vessels that move blood toward the heart. By this definition, the pulmonary vessel that carries oxygenated blood toward heart from the lungs is a vein and not an artery. Capillaries are the site of oxygen/nutrient exchange between the blood and tissues and are the endpoint of oxygenated blood. After oxygen has diffused from the capillaries to the tissues, these same capillaries return deoxygenated blood to the right heart through venules and veins.
The Pulmonary Loop
Deoxygenated blood:
body → vena cava → right atrium→ tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs
Oxygenated blood:
lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta → body
