VI Международная студенческая научная конференция Студенческий научный форум - 2014

The heart is located in the pericardial sac. The wall of the heart is composed of three layers: external - epicardium, middle - myocardium and internal - endocardium. Endocardium covers the inner surface of the heart chambers, it is formed by a special kind of epithelial tissue - endothelium. The endothelium has a very smooth, shiny surface that provides less friction when blood is moving in the heart.

Connective tissue base of the epicardium of the heart in different parts of the heart, and particularly in the furrows and in the apex includes adipose tissue. Myocardium takes a major part of the heart wall. It is formed of the striated cardiac muscle tissue, whose fibers are arranged in several layers. Atrial myocardium is much thinner than the ventricular myocardium. The degree of the development of the myocardium depends on the amount of work the heart chambers perform. Between the muscle layers of the atria and ventricles lies thick fibrous tissue which formes two fiber rings, left and right, which make it possible for atria and ventricles to contract alternately. On the outer surface of the heart the coronal sulcus corresponds to the fibrous rings. In the walls of the atria there are two muscle layers: superficial and deep. The superficial layer is common for both atria. In the ventricular myocardium there are three muscle layers: the outer, middle and deep. Outer and deep layers are common in both ventricles, the middle surrounds each ventricle separately. The epicardium is smooth, thin and transparent layer. It is visceral pericardium plate. Connective tissue base of the epicardium of the heart in different parts of the heart, and particularly in the furrows and in the apex of the heart includes adipose tissue. Epicardium is fused with myocardium most dense in places where there is the smallest accumulation or absence of adipose tissue. Pericardium or pericardial sac, has the shape of a truncated cone with a lower base, located on the diaphragm, and the top, extending almost to the level of the angle of the sternum. In width it extends more to the left than to the right. In the pericardium there are three parts: front (sternocostal) part, lowback (diaphragmatic) part and two lateral - right and left - mediastinal parts.