The heart is made up of four chambers. The ones at the bottom are called right and left ventricles and those at the top are the left and right atria. The left and right sides are divided by the septum, a thin wall between them. The ventricle is connected to its corresponding atrium with a valve which helps pump the blood from one chamber to the other.There are also four crucial vessels connected to these chambers. The right atrium receives deoxygenated blood from the rest of the body through the VENA CAVA; the right ventricle then pumps this deoxygenated blood to the lungs through the PULMONARY ARTERY; the blood returns oxygenated through the PULMONARY VEIN to the left atrium; and finally the left ventricle pumps this clean oxygenated blood to the rest of the body through the AORTA.