What is the term for the lower chamber of the heart that receives blood from the atrium?

The term for the lower chamber of the heart that receives blood from the atrium is "ventricle." The heart consists of four chambers: two atria (upper chambers) and two ventricles (lower chambers). The ventricles are responsible for pumping blood out of the heart; the right ventricle sends deoxygenated blood to the lungs, while the left ventricle pumps oxygenated blood to the rest of the body.

In this context, the ventricles are positioned beneath the atria and receive blood that flows down from the atria when they contract. This anatomical arrangement is crucial for maintaining efficient blood circulation, as it ensures that blood is directed appropriately to the lungs and the body.

The other choices do not accurately describe the lower chamber of the heart. The aorta is a major artery that carries blood away from the heart, the atrium refers to the upper chambers that receive blood returning to the heart, and veins are blood vessels that carry blood toward the heart. Therefore, "ventricle" is the correct term for that specific part of the heart's anatomy.