The heart is a dual pump that circulates blood through systemic and pulmonary tissues. The systemic circulation is from the left ventricle through the body to the right atrium. The pulmonary circulation is from the right ventricle through the lungs to the left atrium.
The wall of the left ventricle wall is thicker than that of the right ventricle, as it must pump against the higher pressure of the systemic circulation. Thus, the right heart carries deoxygenated blood to the lungs and has thin walls. The left heart carries oxygenated blood to the system and has thick walls.
Arteries carry blood away from heart. Pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs. The aorta is a large artery that arises from the left ventricle and supplies the systemic circulation.
Veins carry blood toward the heart. Thus, pulmonary veins carry oxygenated blood from the lungs to the left atrium. Deoxygenated blood from the systemic circulation returns to the right atrium through the superior and inferior vena cava, which are large veins.
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