The heart is composed of three main layers, each with distinct structures and functions:
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Endocardium:
- Structure: This is the innermost layer of the heart, made up of a thin layer of endothelial cells that line the heart chambers and cover the heart valves.
- Function: The endocardium provides a smooth surface for blood to flow over, reducing friction and preventing blood clotting. It also helps to conduct electrical signals that regulate heartbeats.
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Myocardium:
- Structure: The myocardium is the thick, muscular middle layer of the heart and is composed of cardiac muscle tissue. It is responsible for the heart's contractile function.
- Function: The primary function of the myocardium is to contract and pump blood throughout the body. This layer is also responsible for the heart's ability to withstand the pressure generated during contraction and to adapt to varying demands for blood flow.
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Epicardium:
- Structure: The epicardium is the outer layer of the heart, made of connective tissue and a layer of epithelial cells. It is also known as the visceral layer of the serous pericardium.
- Function: The epicardium serves as a protective layer for the heart, providing support and reducing friction between the heart and surrounding structures. It also contains blood vessels, nerves, and lymphatics that supply the heart.
Together, these three layers enable the heart to function effectively as a pump, circulate blood, and maintain overall cardiovascular health.