Which two heart chambers have the thickest walls?

Answers:
The heart's ventricles are what pump the blood out of the heart, to the lungs (right ventricle) for oxygen and to the the body (left ventricle) for circulation. The heart's atria merely collect incoming blood from the body (right atrium) and from the lungs (left atrium) and push it into the ventricles. Because of the greater power needed in the ventricles, more cardiac muscle is needed, and so the chamber walls are thicker. The ventricles are located on the bottom half of the heart.

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the atria two upper chambers

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