The Heart's Chambers and Valves
The Heart's Chambers and Valves
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By Richard N. Fogoros, MD
Updated January 09, 2017
The function of the heart is to pump the blood that bathes every organ of the body. The blood carries the oxygen and nutrients vital to the tissues and removes waste products. If the pumping action of the heart is disrupted, the body's organs begin to fail very quickly. So life itself is dependent on the efficient, continuous operation of the heart.
The heart is a muscular organ roughly the size of your fist.
As the heart muscle contracts or squeezes, it propels the blood out into the vascular system. The heart's chambers and valves are arranged to direct the flow of the blood as the heart beats.
Heart’s Chambers and Valves
The heart has four chambers. The two ventricles (right and left) are muscular chambers that propel the blood out of the heart. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to all other organs.
The two atria (right and left) hold the blood returning to the heart, and at just the right moment empty into the right and left ventricles. 
The  four heart valves  (tricuspid, pulmonary, mitral and aortic) keep the blood moving in the right direction through the heart.
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 Heart Pump
The right heart pump consists of the right atrium, tricuspid valve, right ventricle, pulmonic valve, and pulmonary artery.
Its job is to make sure “used” blood gets reloaded with oxygen. Oxygen-poor blood returning to the heart from the body’s tissues enters the right atrium. When the atria contract, the tricuspid valve opens and allows the blood to be pumped from the right atrium to the right ventricle. Then, when the right ventricle contracts, the tricuspid valve closes (to prevent blood from washing backwards to the right atrium), and the pulmonic valve opens — so blood is ejected from the right ventricle and out to the pulmonary artery and the lungs, where it is replenished with oxygen.