The lower chambers of the heart are the ____.

The correct answer is Ventricles. The heart is comprised of four main chambers: two upper chambers known as atria and two lower chambers known as ventricles. The ventricles are responsible for pumping blood out of the heart. The right ventricle pumps deoxygenated blood to the lungs for oxygenation, while the left ventricle pumps oxygenated blood to the rest of the body. This distinction is crucial in understanding the heart’s anatomy and function.

Atria are the upper chambers of the heart, receiving blood from the veins, which distinguishes them from the lower chambers. Valves are structures that prevent the backflow of blood within the heart but are not chambers themselves. The septum is the wall that separates the left and right sides of the heart but does not represent a chamber. Understanding the roles and locations of these structures is essential for comprehending the cardiovascular system's function.