Which layer of the heart lines the chambers and valves?

The endocardium is the innermost layer of the heart and is significant because it lines the chambers of the heart as well as the heart valves. This layer consists of a thin layer of endothelial cells, which helps facilitate smooth blood flow within the heart and prevents turbulent flow that could lead to clot formation. By providing a smooth surface, the endocardium plays a crucial role in maintaining the efficiency of the heart's pumping action and protecting the heart's inner structures.

In contrast, the myocardium is the thick, muscular middle layer of the heart responsible for the contraction that pumps blood. The epicardium, which is the outer layer, provides a protective coating and can also house blood vessels that supply the heart. The pericardium is a double-walled sac that surrounds the heart and provides cushioning and protection from infection and trauma, but it does not line the chambers or valves. Understanding the distinct roles of each layer helps in comprehending the anatomy and function of the heart more clearly.