The left and the right sides of the heart are separated by walls of tissue known as septums. There are two septums in the heart. The atrial septum separates the left and the right atria, and the ventricular septum separates the left ventricles from the right ventricles.
The heart is a four-chambered muscular structure that pumps oxygen-poor blood and oxygen-rich blood throughout the body. Each side of the heart has a ventricle and an atrium that work together to push blood through the chambers of the heart. In general, the ventricles pump the blood, while the atria collect the blood before pushing it out of the heart into the pulmonary or systemic circulation.