Your heart started beating 6 weeks after you were conceived, and it will continue to beat about 100,000 times a day, resting only between beats, until the end of your life. Its only function is to circulate the blood that nourishes and sustains your every cell. It pumps the 6 qts of blood your body contains through your entire circulatory system - over 60,000 miles of arteries, veins, and capillaries, more than twice the distance around the equator of the Earth - and it does that three times a minute.

Your heart is the central hub of your body. Without it, nothing else can function. An organ that vital to your well-being can't stop working. But what if it does?

Coronary Arteries and Blood Supply
Like every other organ in your body, your heart needs to be supplied with blood and the life-sustaining oxygen in it. But the blood flowing through its chambers doesn't nourish the heart itself. Your heart gets its blood supply from the coronary arteries, so called because they wrap around the heart like a crown. ("Coronary" is the Latin word for crown.) Two main coronary arteries branch out of the aorta, the left main coronary artery and the right coronary artery. These large coronary arteries are about the width of a drinking straw and gradually taper as they descend on your heart. The left main coronary artery divides into two branches called the left anterior descending artery and the circumflex artery. The right coronary artery branches into the posterior descending artery and the marginal artery. These arteries branch into smaller and smaller arteries, some of which penetrate inside your heart. The arteries eventually branch into capillaries, some so fine that it would take ten of them lying side by side to form the thickness of a human hair. Your capillaries deliver oxygen and nutrients and remove waste from your heart's cells.

But the coronary arteries can become clogged, or even completely blocked, with a hard, fatty substance called plaque. This disease is termed atherosclerosis, or hardening of the arteries, and its results can be disastrous.

More on this topic

Understanding Heart Attacks (VIDEO)
Your Heart Needs Blood
Your Beating Heart
Atherosclerosis & Cholesterol
Angina & Coronary Heart Disease
Heart Attack Symptoms
What Is a Heart Attack?
Risk Factors & Diagnosis
Treating Heart Attacks
Restoring Blood Flow
Rehabilitation

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