The Heart

Composition of the Human Heart :

•   Outer Covering - Pericardium: The heart and the roots of its major blood vessels are surrounded and enclosed by a sac-like structure called pericardium. It comprises of two parts - the outer fibrous pericardium, made of dense fibrous connective tissue and an inner double-layered membrane (parietal and visceral pericardium). The fibrous pericardium is attached to thespinal column, diaphragm and other parts of the body, by ligaments. The double-layered membrane consists of an inner layer called visceral pericardium, outer layer called parietal pericardium (fused to fibrous pericardium) and a pericardial cavity (between the two layers), which contains serous fluid - pericardial fluid. This fluid helps in reducing the friction caused by the contractions of the heart.
•   Heart Wall: The wall of the heart is made up of three layers of tissues - outer epicardium, middle myocardium and the inner endocardium. The outer epicardium functions as a protective outer layer, which includes blood capillaries, lymph capillaries and nerve fibers. It is similar to the visceral pericardium, and consists of connective tissues covered by epithelium (membranous tissue covering internal organs and other internal surfaces of the body). The inner layer called myocardium, which forms the major part of the heart wall, consists of cardiac muscle tissues. These tissues are responsible for the contractions of the heart, which facilitates the pumping of blood. Here, the muscle fibers are separated with connective tissues that are richly supplied with blood capillaries and nerve fibers. The inner layer called endocardium, is formed of epithelial and connective tissue that contains many elastic and collagenous fibers (collagen is the main protein of connective tissues). These connective tissues contain blood vessels and specialized cardiac muscle fibers called Purkinje fibers. This layer lines the chambers of the heart and covers heart valves. It is similar to the inner lining of blood vessels called endothelium.

Great explanation dude.

thank u