The inside of your heart is divided into four chambers. The two upper chambers of your heart are called the atria. They receive and collect blood. The two lower chambers of your heart are called ventricles. The ventricles pump blood out of your heart to other parts of the body.
Blood enters the right atrium of your heart from the superior and inferior vena cavae. From the right atrium, blood is pumped into the right ventricle. From the right ventricle, blood is pumped to your lungs through the pulmonary arteries. Oxygen-rich blood coming from your lungs enters through the pulmonary veins into your heart’s left atrium. From the left atrium, the blood is pumped into the left ventricle. The left ventricle pumps the blood to the rest of your body through the aorta.
Source: National Institutes of Health
Anatomy, Patient Education
May 6, 2008