You may have heard the expression "the heart of the matter" as a way of describing something that is "most important" or "central." While all the body's systems, tissues and organs are vital for functioning, the heart is without a doubt critical. 

The Structure and Function of the Heart

In an average lifespan, a person's heart will beat 2.5-3 billion times, pushing blood to all parts of the body. The heart is a relatively small, muscular organ that is roughly the size of your fist. Exactly how does such a small muscle push blood through arteries and other blood vessels to all of the tissues in your body?

The heart is able to push blood with enough force into your arteries because of its structure. It truly is a pump.

The heart is divided into four chambers, the left and right atria and the left and right ventricles. A thick wall called the septum separates the left side of the heart from the right. The valves, or one-way doors within the heart, separate the atria from the ventricles. The valves carefully regulate blood flow through the heart’s chambers. The walls of the heart and the valves keep the blood on a “one-way street” through the heart and out to the body and back.

When blood arrives at the heart, it comes through veins from the body. Upon arrival at the heart, the blood is depleted of oxygen. It enters the right atrium of the heart. A valve called the tricuspid valve prevents the blood from flowing downward into the right ventricle until the appropriate time. Then the valve opens, the blood flows into the ventricle, and the ventricle contracts, forcing the blood through the open pulmonary valve and into the pulmonary artery. The pulmonary artery then carries the blood to the lungs to release carbon dioxide and pick up oxygen.

From the lungs, blood returns to the heart through the pulmonary veins and enters the left atrium. The mitral valve keeps the blood in that chamber until it is time for it to move to the left ventricle. The ventricle contracts, and the blood is forced through the open aortic valve and into the aorta, which is the largest artery in the body. The aorta distributes blood to the smaller arteries and other blood vessels that supply your entire body with oxygenated blood.

All of the above happens continuously in your body if you have a normal, healthy heart and arteries. For some people, however, difficulties with the heart and arteries begin with birth. Cardiovascular defects that are present at birth are referred to as congenital heart disease. These defects can occur in the structure of the heart wall and valves, or they may relate to the heart's rhythm or other cardiovascular functions.

Other people who are diagnosed with cardiovascular disease are born with a healthy heart and arteries, but they acquire heart disease over time. Lifestyle and genetic factors can together contribute to problems such as impaired valve functioning or narrowed arteries.

Unfortunately, cardiovascular disease is the leading cause of death in the United States and in most of the rest of world. The good news is some forms of cardiovascular disease can be prevented by controlling risk factors, plus new research and medical advances are leading to better treatment options for patients with either congenital or acquired heart disease. For example,

• Lifestyle changes and medications can be used to help many patients minimize risk factors for heart disease and manage cardiovascular disease.
• Structural problems with the heart's wall and valves can often be corrected through surgery or, in some case, newer minimally invasive procedures.
• Narrowed arteries can be opened through a procedure called angioplasty and through the insertion of stents (tubes to hold the artery open).

The Heart's Electrical System

Over the course of your life so far, you were most likely familiar with the heart because of its beating. Perhaps you heard your heartbeat through a stethoscope or listened to someone else's heartbeat. Or maybe you put two fingers to your wrist or neck to feel your pulse. Your pulse is your heartbeat sensed in your arteries.

Your heartbeat is the relaxing and contracting of your heart’s atria and ventricles. This process is stimulated by electrical impulses that travel through your heart and regulate your heartbeat. The electrical impulse begins in the sinoatrial (SA) node in the top of the right atrium and travels through the muscles of both atria. The atria contract in response. The electrical impulse is then picked up by the atrioventricular (AV) node, which is between the atria and the ventricles, and passed to the fibers of the His-Purkinje system. The ventricles fill with blood from the atria before the electrical impulse causes them to contract. Once the ventricles do contract, they force the blood out of the heart and to the lungs and body.

The timing of the flow of blood through the heart is key for good health. Problems with the heart's electrical system can be life threatening. A patient's care team may advise implantation of a pacemaker or other treatment. For more information about the heart’s electrical system, how problems can develop and treatment options, visit the website of the Heart Rhythm Society.