The Heart and How It Works


Before further discussing congestive heart failure, it isimportant to briefly review the basic make-up of theheart and how it works to circulate your blood.

The heart is a muscular organ in the middle of yourchest. It is approximately the size of your clenched fistand it is the “pump” that circulates all the blood in yourbody. The contractions of this muscular pump are theheartbeats you can feel and that your doctor listens towith a stethoscope

Figure 1 : Heart anatomy

The heart is divided into four chambers. There aretwo atria and two ventricles. The atria, which are located at the top of the heart, are smaller and have thinner walls. The atria are connected to the ventricles below them. The atrium and ventricle worktogether as a team to pump blood out of the heart.Although they are connected to each other, each oneof the two sets of atria and ventricles pumps blood toa different place.

The right atrium and ventricle take blood from thelargest vein in the body (the vena cava) and pump itinto the lungs for oxygenation. The left atrium andventricle take blood coming from the lungs and pumpit into the rest of the body.

When your blood circulates, it moves blood from theveins in your body toward your heart. This blood inyour veins is low in oxygen and high in carbon dioxide.The blood enters the right upper chamber of yourheart, the right atrium.When the atrium contracts, theblood is moved into the larger chamber below it calledthe right  ventricle. Here, the blood from the veins,which is filled with carbon dioxide, is propelled intothe lungs. The lungs are able to get rid of the carbondioxide and put oxygen into the blood. This oxygenatedblood circulates out of the lungs and into the left sideof the heart.

The blood from the lungs enters the left atrium andwhen this chamber contracts, it pushes the blood intothe largest chamber of the heart, the left ventricle.The left ventricle’s job is to push the blood into theaorta, the largest artery in the body. Because thischamber supplies most of the heart’s pumping power,it’s larger and has more muscle mass than the otherchambers. From the aorta, the blood circulates to allthe organs of the body, bringing oxygen and carryingaway carbon dioxide.