The heart is responsible for bringing oxygen-rich, or oxygenated, blood to the rest of the body. Each time the heart beats, it squeezes (contracts) to push blood through the body.

The heart is divided into two sides, the right and the left. Each side has two chambers: an atrium (upper chamber) and a ventricle (lower chamber).

This is how your blood flows through the chambers of the heart:

• Unoxygenated blood enters the heart through two large veins, the Superior Vena Cava and the Inferior Vena Cava, which deliver the blood to the right atrium (the first chamber of the heart). The blood then flows to the right ventricle.
• After the blood leaves the right ventricle, it goes through the pulmonary artery to both lungs, where the blood gets oxygenated.
• Oxygenated blood flows back to the heart through the pulmonary veins and into the left atrium. The blood then flows into the left ventricle.
• Once the blood leaves the left ventricle, it goes to the aorta, which sends oxygenated blood to the brain, coronary arteries and the rest of the body.

Heart Valves

As the blood passes through the different chambers of the heart, it passes through valves. The heart has four valves: the tricuspid, pulmonary, mitral and aortic. As the heart muscle contracts and relaxes, valves ensure that blood flows in the right direction to the right place.

• The tricuspid valve is between the right atrium and the right ventricle.
• The pulmonary valve is between the right ventricle and the pulmonary artery.
• The mitral valve is between the left atrium and the left ventricle.
• The aortic valve is between the left ventricle and the aorta.

Valves have flaps, called leaflets, that open and shut. Some valves have two flaps, and some have three.

A normal pulmonary valve, aortic valve and tricuspid valve each has three leaflets. A normal mitral valve has two leaflets.

If one of your heart valves does not work properly, this can affect blood flow. One type of valve disease, called regurgitation, occurs when the leaflets of the valve do not work properly. This allows the blood to flow in the wrong direction. The other type of valve disease occurs when the leaflets of the valve narrow, which makes it more difficult for blood to flow forward. This is called stenosis.

Learn more:

• Aortic Valve Disease
• Bicuspid Aortic Valve Disease
• Marfan Syndrome and Related Disorders
• Mitral Valve Disease
• Tricuspid Valve Disease

Coronary Arteries

Just like any other organ, the heart needs oxygen. The heart muscle gets oxygen through blood vessels that wrap around the surface of the heart. They include:

• The left main coronary artery, which branches into the circumflex coronary artery and the left anterior descending coronary artery.
• The right coronary artery.

Learn more:

• Coronary Artery Disease