Anatomy of the Heart
The heart has two “sides.” and is made up of four chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles A wall of muscle called the septum separates the eft and right atria and the left and right ventricles.
Heart’s Chambers and Valves
The four heart valves (tricuspid, pulmonary, mitral and aortic) open and close at just the right moment to keep the blood moving in the proper direction through the heart.
Blood circulation
It is helpful to visualize the heart functioning as two separate pumps, working in series; the right heart pump, and the left heart pump.
The right side of the heart accepts “used” blood that is returning from the tissues of the body, and pumps that blood into the lungs, where it is replenished with oxygen. The left side of the heart accepts replenished blood from the lungs, and then pumps that blood out to all the body’s organs.
The two atria (right and left) accept the blood returning to the heart (from the body’s tissues and from the lungs, respectively). At just the right moment, the right and left atria empty their accumulated blood into the right and left ventricles.