Which term refers to the force exerted as the heart pumps from the left ventricle into the arteries and out into the body?

The atria

Actually, it is the contractions (squeezing) of the ventricles (the lower parts of the heart), not the atria (the upper parts), that do the pumping. That's why the lower part of the heart is larger, and the muscular walls are thicker.

The atria receive the blood from the body and pump it down into the ventricles.