The heart is divide into 4 chambers.

• The two chambers on top are called the right atrium and the left atrium.
• The two chambers on the bottom are called the right ventricle and the left ventricle.

Blood moves in and out of the heart in the pattern described below.

• Blood from the body flows^* into the right atrium through a large vein called the vena cava.
• Blood flows from right atrium to the right ventricle.
• Blood flows from right ventricle to the lungs through the pulmonary artery.
• Blood flows from lungs back to the left atrium through the pulmonary vein.
• Blood flows from left atrium to the left ventricle.
• Blood flows from left ventricle into a large artery called the aorta.
• This blood splits into two branches. One takes blood to the brain. The other takes blood to the rest of the body.