Your heart is a strong fist-sized muscle situated in the centre of your chest and tilted a little to the left. It pumps blood through the blood vessels thereby delivering oxygen and nutrients to all parts of the body. The heart has four chambers: the two upper chambers called atria act as receiving chambers. The two lower chambers, the ventricles, are the pumping chambers which tirelessly perform the actual work of pumping blood: 60 to 90 times a minute, 24 hours a day, for as long as you live. During an average lifetime the average heart beats over two billion times!
A thick band of muscle, the septum, separates the heart into two sets of pumps, the left and the right. Each side has a different function in the heart's pumping action. The right side of the heart receives the 'used up' stale blood returning from the organs of the body and pumps it to the lungs. As blood passes through the lungs it picks up a fresh supply of oxygen while carbon dioxide is thrown out. The left side of the heart receives oxygen rich blood from the lungs and pumps it out through the main artery of the body, the aorta, which in turn delivers blood to different parts of the body. The force with which the left ventricle pumps the blood is sufficient to propel it 6 feet up in the air! Since the left side of the heart has to work more than the right side, it has more muscle mass and is thicker than the right side.