Britannica Sources used in this answer

How are the right and left sides of the heart different?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Illustration of a human heart cross-section showing four chambers-left and right atria and ventricles-with labeled major blood vessels. An inset highlights cardiac muscle tissue, showing myocytes and intercalated disks. — human cardiovascular system The human heart is both a pump and a muscle. Its four chambers move blood efficiently, while cardiac muscle cells joined by intercalated disks synchronize each contraction.

The human heart is divided by septa into right and left halves, each consisting of an upper atrium and a lower ventricle. These sides differ significantly in their function, blood composition, and anatomy:1

Function and Blood Flow: The right side receives oxygen-poor, carbon dioxide-rich blood from the body via the venae cavae and pumps it to the lungs for gas exchange. The left side receives oxygenated blood from the lungs via the pulmonary veins and pumps it through the aorta to the rest of the body.12
Structural Differences: The left ventricle is more muscular, with walls three times as thick as those of the right ventricle, reflecting the higher pressure required to pump blood throughout the systemic circulation. Additionally, the left atrium is slightly smaller than the right but possesses a thicker wall.1
Vascular Supply: The left coronary artery is generally larger and more critical than the right, as it must supply the more muscular left ventricle.3