The smooth, thin membrane that lines the chambers of the heart and forms the surface of the heart valves is the:
A.
Pericardium.
B.
Endocardium.
C.
Myocardium.
D.
Epicardium.
The correct answer and Explanation is :
The correct answer is B. Endocardium.
The endocardium is the smooth, thin membrane that lines the inner chambers of the heart and forms the surface of the heart valves. It is a delicate layer of simple squamous epithelium, supported by connective tissue, and its primary role is to ensure a smooth surface for blood to flow through the heart’s chambers, reducing the risk of turbulence that could cause clotting or damage to blood cells. This layer is continuous with the endothelial lining of blood vessels, maintaining a seamless passageway from the heart to the circulatory system.
The pericardium (A) is a double-walled sac that encloses the heart and the roots of the great vessels. It serves as a protective layer, reducing friction between the heart and surrounding structures during contraction. The outer layer is fibrous, while the inner layer is serous, with a fluid-filled space between them to facilitate smooth heart movement.
The myocardium (C) refers to the thick, muscular middle layer of the heart wall, composed primarily of cardiac muscle. This is the layer responsible for the heart’s powerful contractions that pump blood throughout the body. The myocardium varies in thickness between different chambers, being thicker in the ventricles, particularly the left ventricle, which has to pump blood to the entire body.
The epicardium (D) is the outermost layer of the heart and is synonymous with the visceral layer of the pericardium. It serves as another protective layer, providing structural support and producing a small amount of serous fluid to minimize friction.
Thus, while the pericardium, myocardium, and epicardium all play crucial roles in heart function, it is the endocardium that specifically lines the heart’s chambers and forms the surface of its valves.