The heart is the most hardworking part of the human body. From the minute it is created in your mother’s womb, it continues to beat till the last moment of your life. The heart is approximately the size of your fist. Open your fist and close it, as long as you can. Try doing it as though you were trying to crack a walnut. You will find that you cannot do it for more than a few minutes. Yet your heart works even harder, at the same pace, for your whole life. This is because of special nature of the cardiac muscle. The cardiac muscle will contract without any signal from the nervous system. So usually it is believed that you have no control over your heartbeat, which is a part of the autonomic system. However, biofeedback systems can help you slow down your heartbeat, as recent research has shown. Meditation techniques also slowdown the heartbeat.
The heart supplies blood and is the pump, which controls the circulatory system. It weighs 340 gms and is about 15 cms long and 10 cms across. Protected by the hard bony ribs, breastbone cage and backbone, the heart provides fuel for all parts of the body, feeding the cells of the body with oxygen. When the blood has given up its oxygen to the cells, it has a bluish tinge. The pulmonary arteries or arteries from the lungs collect the de-oxygenated blood and carry it to the lungs, where it once more picks up oxygen and releases carbon-dioxide. The pulmonary veins carry oxygenated blood (blood rich in oxygen) back to the heart, so that it can feed every cell of your body. The arteries carry deoxygenated blood away from the heart, while the veins carry blood to the heart. It is estimated that everyday, the heart pumps blood through 90,000 kilometres of blood vessels.