How many layers compose the heart structure?

The heart is composed of three distinct layers, each serving a critical function. These layers are the epicardium, myocardium, and endocardium.

The outermost layer, the epicardium, provides a protective layer for the heart and also includes blood vessels, nerves, and lymphatics that supply the heart tissue. The middle layer, the myocardium, is primarily made up of cardiac muscle tissue; this is the thickest layer and is responsible for the contractile function of the heart, allowing it to pump blood effectively throughout the body. The innermost layer, the endocardium, lines the heart chambers and valves, ensuring smooth blood flow and helping to prevent clot formation.

This structured arrangement of three layers is essential for the heart's durability, efficiency, and functionality, which is why the correct answer is three layers.