What is the endocardium?

What is the endocardium?

• A. The innermost layer of the heart wall that covers the internal surface of the heart and the external surface of the valves.
• B. The thick muscular layer responsible for pumping blood.
• C. The visceral pericardial covering of the heart.
• D. The fibrous external layer of the heart.

Answer: (A)

Endocardium is the innermost layer of the heart wall, lining the chambers and covering the valve surfaces. It’s a thin, smooth layer of endothelial cells (with a subendocardial connective tissue layer) that creates a friction-reducing surface for blood flow and provides a barrier between the blood and the muscular heart tissue. This inner lining is distinct from the thicker muscular middle layer, which is the myocardium and does the pumping, and from the outer layers: the epicardium (visceral pericardium) that covers the heart’s exterior, and the fibrous pericardium forming the tough outer sac.

Endocardium is the innermost layer of the heart wall, lining the chambers and covering the valve surfaces. It’s a thin, smooth layer of endothelial cells (with a subendocardial connective tissue layer) that creates a friction-reducing surface for blood flow and provides a barrier between the blood and the muscular heart tissue. This inner lining is distinct from the thicker muscular middle layer, which is the myocardium and does the pumping, and from the outer layers: the epicardium (visceral pericardium) that covers the heart’s exterior, and the fibrous pericardium forming the tough outer sac.