To understand coronary artery disease (CAD), you need to know how your heart works. Your heart is a muscle that pumps blood throughout your body. To work right, your heart needs a steady supply of oxygen. It gets this oxygen from blood supplied by the coronary arteries.

If an artery narrows too much, you can feel chest pain. A heart attack occurs if an artery closes all the way or narrows so much that a blood clot blocks the blood flow.

The most common form of heart disease is atherosclerosis, or hardening of the arteries. Cholesterol joins with calcium and scar tissue and builds up in the arteries. When cholesterol levels are too high, the circulatory system becomes choked—and the result is a dam of plaque that narrows the channels the blood flows through.

Here are important medical terms to know about your condition.

Some risk factors for heart disease are beyond your control, but others, such as smoking or high blood pressure, you can do something about.

If your father or mother has heart disease, that doesn't mean you will automatically develop it, too. It's true that you are more likely to get it than someone who does not have a family history of heart disease, but you can take steps to try to prevent it.

Control your blood pressure, keep your cholesterol in check, and take your medicine as prescribed.

In many cases, the progression to high blood pressure occurs within four years of being diagnosed with prehypertension.

Your heart is a pumping muscle that works nonstop to keep your body supplied with oxygen-rich blood. Signals from the heart’s electrical system set the speed and pattern of the pump’s rhythm. Valves keep the blood moving in one direction, through the heart’s four chambers.

Nonstop flow of blood from the heart to the body and back to the heart again is called circulation. Blood vessels are hollow muscular tubes that carry blood throughout your body, much like pipes circulate water in your home.

The heart has a special system that creates and sends electrical signals. First, signals tell the atria to squeeze. This moves blood to the ventricles. Next, signals tell the ventricles to squeeze. This moves blood to the lungs and body.

Your heart pumps blood through 60,000 miles of vessels. But it gets help in this huge task from your body's other muscles, especially those in the legs.

Every minute of every day, millions of blood cells trek through about 60,000 miles of blood vessels -- enough to stretch from New York City to San Francisco 23 times -- delivering oxygen and nutrients to every tissue. Your cardiovascular system includes your heart and two basic kinds of blood vessels: arteries and veins.

By knowing your heart rate, you can gauge how fit you are and whether you're working out at a moderate pace.

As a patient, understanding the basics of the guidelines can help you take a more active role in your treatment.

A short glossary of medical terms associated with heart disease.

It’s great if you can keep your heart healthy—by not smoking, eating a healthy diet, and getting regular physical activity. But what if you end up needing heart surgery? What should you know about the procedure?

Information and definitions on everything from angina to ventricles.

Not everyone who has had a heart attack needs open-heart surgery, such as a bypass operation.