What type of structures are the four chambers of the heart?

The four chambers of the heart—right atrium, right ventricle, left atrium, and left ventricle—are classified as hollow structures because each chamber contains a space that holds blood. This hollow design is essential for the heart's function of pumping blood throughout the body and receiving blood returning from circulation. The right atrium and right ventricle work together to pump deoxygenated blood to the lungs, while the left atrium and left ventricle handle oxygenated blood, delivering it to the rest of the body.

In addition to being hollow, these chambers are muscular, as they contain thick walls of cardiac muscle tissue that contract to propel blood. However, the defining feature in this context is their hollow nature, which allows for the reservoir function of the chambers.

While elasticity is a characteristic of certain structures in the heart, such as the arteries that accommodate changes in blood flow, the primary description of the heart chambers revolves around their hollow structure, making them effective at their role in circulation.