Heart Disease Healthy

Understanding how the healthy heart works may be the first step to maintaining heart health and protecting ourselves from heart disease.

The heart is a fist-sized organ containing four hollow chambers. When the muscular walls of the heart contract, the chambers constrict, forcing the flow of blood through each one. The blood moves through the first two chambers, then flows out to the lungs to absorb oxygen and dispose of carbon dioxide. The blood then returns to the heart, flows through the other two chambers, and exits to deliver oxygen to the body.

The Healthy Heart: Right Side

If you examine a drawing of the heart, you will see a set of large blue veins, the vena cavae, on the left side of the picture (or the right side of the heart as it is oriented in the body). After the blood has delivered its supply of the oxygen to the body, it returns to the heart through these veins. The oxygen-poor blood is welcomed back into the heart through the right atrium (above) and then is swept into the large right ventricle (below). From there the blood is moved out through the pulmonary arteries to the lungs, where it absorbs a fresh supply of oxygen.

The newly oxygenated blood then returns to the heart through the pulmonary veins and enters the left chambers.

The Healthy Heart: Left Side

Oxygen-rich blood is drawn from the lungs back into the heart via the left atrium. From there it is pushed into the left ventricle, and then out into the body by way of the aorta–the large pink arching artery at the top of the heart muscle. After delivering oxygen and nutrients throughout the body, the blood returns to the heart once more through the vena cavae and the cycle continues.

The Healthy Heart: Valves

The left and right sides of the heart are divided by a wall called the septum. Valves connect the upper and lower chambers on each side of the septum and also control blood flow out through the pulmonary arteries and in through the pulmonary veins. This adds up to four valves total. In a healthy heart, these valves open and close in perfect rhythm, keeping the blood flowing in only one direction as the chambers contract.

A natural electrical pacemaker called the sino-atrial node (SA) controls the heart rate, or the rate of these contractions. If the SA and other nodes are working properly and the heart valves are healthy, the blood in each chamber will never back up or flow backwards.

Healthy Heart Sounds

To protect your heart health and prevent heart disease, it’s a good idea to exercise, eat well, control your heart rate and schedule a regular health check. When you visit the doctor for a health check, she may measure your heart rate and listen for the single, sharp “lub-dub” sound a healthy heart makes as the valves open and close. Extra sounds may indicate valve damage or defects, and backed-up blood may also create a sound, which we call a murmur. The significance of a murmur depends on where it occurs in the cycle. The doctor performing your health check may listen for these sounds using a stethoscope and will tell you if she hears something irregular and if more tests are necessary.


Columbia University Department of Surgery. (2010). Healthy heart anatomy. Retrieved October 25, 2010, from http://www.cumc.columbia.edu/dept/cs/pat/cardiac/anatomy.html

The Auscultation Assistant. (2010). Physiology of murmurs. Retrieved October 25, 2010, from http://www.wilkes.med.ucla.edu/Physiology.htm

The National Heart Lung and Blood Institute. (2010). How the heart works. Retrieved October 25, 2010, from http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_anatomy.html