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heart

heart

/härt/

Noun

The heart is a four-chambered pump that can be organized in two different ways. On one hand, the upper chambers, called the atria, squeeze blood into the lower chambers, known as the ventricles. By doing so, the heart ensures that the ventricles are filled with blood before they contract. On the other hand, the right side of the heart is designed to pump blood into the pulmonary circulation, or the part of the vasculature that leads to and away from the lungs. The left side of the heart pumps blood returning from the pulmonary circulation out to the rest of the body.