The heart is primarily composed of three layers of tissue and specialized muscle cells.
The Three Layers of Heart Tissue
- Endocardium: This is the thin, inner lining of the heart chambers and covers the heart valves. It's a delicate layer that provides a smooth surface for blood flow.
- Myocardium: This is the thick, middle layer, and the most significant part of the heart. It's made of cardiac muscle tissue, responsible for the heart's powerful contractions that pump blood throughout the body.
- Epicardium: This is the thin, outer layer of the heart. It's a serous membrane that protects the heart and reduces friction.
Cellular Composition
Histologically, the heart is mainly composed of cardiomyocytes (heart muscle cells) and connective tissue. The connective tissue, which includes dense connective tissue with elastic fibers, provides structural support.
Heart Chambers and More
While the layered tissue structure is key, the heart is also divided into four chambers: two atria (upper chambers) and two ventricles (lower chambers). These chambers work together to effectively pump blood. The heart also contains valves that ensure unidirectional blood flow.
