The heart is the Central organ of the circulatory system, providing movement of blood through the vessels.
the human heart structure

Fig. 1-3. The human heart. Fig. 1. Heart opened. Fig. 2. A conductive system of the heart. Fig. 3. Vessels of the heart: 1-superior Vena cava; 2-aorta; 3-left atrium; 4-the aortic valve; 5-butterfly valve; 6-the left ventricle; 7-papillary muscles; 8-interventricular septum; 9-right ventricle; 10-tricuspid valve; 11-the right atrium; 12-the lower hollow vein; 13-sinus node; 14 atrioventricular node; 15-barrel bundle branch; 16-the right and left leg bundle branch; 17-right coronary artery; 18-to-left coronary artery; 19-big Vienna heart.

The human heart is four-chamber muscular bag. It is located in the anterior mediastinum, mainly in the left side of the chest. The rear surface of the heart is adjacent to the diaphragm. From all sides it is surrounded with light, with the exception of the front surface, directly adjacent to the chest wall. In adults length heart 12-15 cm, the transverse size 8-11 cm, front-back dimensions of 5-8 see the Weight of the heart 270-320, the Walls of the heart is formed mainly muscle - tissue infarction. The inner surface of the heart is lined with a thin membrane - endocardium. The outer surface of the heart is covered with serous membrane - epicardium. The last level of large vessels departing from the heart, is turned outwards and downwards and forms the pericardium (the pericardium). Extended rear-upper part of the heart is called the base, narrow front-lower part - tip. Heart consists of two Atria, which are located in the upper part, and two ventricles, which are located in the lower part. Lengthways heart is divided into two interconnected half - right and left, each of which consists of auricle and ventricle (Fig. 1). The right atrium is connected with the right ventricle and left atrium from the left ventricle atrioventricular holes (left and right). Every atrium has a hollow bone, called loops. In the right atrium into the upper and the lower hollow vein carrying venous blood from a large range of blood and veins of the heart. From the right ventricle goes pulmonary trunk on which the venous blood enters the lungs. In the left atrium into four pulmonary veins that carry from light enriched with oxygen in arterial blood. From the left ventricle goes aorta, which the arterial blood is sent to the systemic circulation. The heart has four valves, regulating the direction of blood flow. Two of them are located between the Atria and the ventricles, covering atrioventricular holes. The valve between the right atrium and right ventricle consists of three wings (tricuspid valve between the left atrium and the left ventricle is of two valves (butterfly, or mitral valve). Shutters of these valves is formed by duplikatory inner lining of the heart and attached to the fibrous ring, limiting each atrioventricular hole. To the free edge of the valves are attached tendon threads connecting them with the papillary muscles located within the ventricles. Last prevent "inversion" of valve cusps in the cavity of the atrium at the time of contraction of the ventricles. The other two valves are located at the entrance to the aorta and the pulmonary trunk. Each of them consists of three semilunar valves. These valves, closing in relaxation of the ventricles, prevent back-flow of the blood into the ventricles of the aorta and the pulmonary trunk. The Department of the right ventricle of the start of the pulmonary trunk and left ventricle, where rises aorta, called arterial cone. The thickness of the muscular layer in the left ventricle - 10-15 mm in the right ventricle is 5-8 mm in Atria - 2-3 mm
In the myocardium has a set of specific muscle fibers that make up the conducting system of the heart (Fig. 2). In the wall of the right atrium, near the mouth of the top Vena cava, laid sinus node (Kisa - Fleck). Part of fibers of this node in the field of Foundation of the tricuspid valve forms another node - atrioventricular (Asifa - Tavares). From it begins atrioventricular bundle of his, which in interventricular septum is divided on two legs - right and left, going to the appropriate ventricles and ends below the endocardium separate fibers (Purkinje fibers).
The blood supply to the heart is through the coronary (coronary) arteries, right and left, which depart from the bulbs of the aorta (Fig. 3). Right coronary artery supplies blood to the predominantly back wall of the heart, the back of the interventricular septum, the right ventricle and auricle and partly the left ventricle. The left coronary artery supplies the left ventricle, the front of the interventricular septum and the left atrium. Branch left and right coronary arteries, broken down to the smallest branches, form a capillary network.
Venous blood from the capillaries through the veins of the heart enters the right atrium.
Innervation of the heart is carried out by branches of the vagus nerve and branches of sympathetic trunk.

anatomy of the heart
Fig. 1. Cut to the heart through the Atria and ventricles (front view). Fig. 2. The arteries of the heart and coronary sinus (Atria, pulmonary trunk and the aorta removed, top view). Fig. 3. The cross-sections of the heart. I - the upper surface fibrillation; II - cavity of the right and left Atria, holes of the aorta and the pulmonary trunk; III - section at the level of atrioventricular holes; IV, V and VI - sections of the right and left ventricles; VII - the area of the apex of the heart. 1 - atrium sin.; 2 - v. pulmonalis sin.; 3 - valva atrioventricularis sin.; 4 - ventriculus sin.; 5 - apex cordis; 6 - septum interventriculare (pars muscularis); 7 - m. papillaris; 8 - ventriculus dext.; 9 - valva atrioventricularis dext.; 10 - septum interventriculare (pars membranacea); 11 - valvula sinus coronarii; 12 - mm. pectinati; 13 - v. cava inf.; 14 - atrium dext.; 15 - fossa ovalis; 16 - septum interatriale; 17 - vv. pulmonales dext.; 18 - truncus pulmonalis; 19 - auricula atrii sin.; 20 - aorta; 21 - auricula atrii dext.; 22 - v. cava sup.; 23 - trabecula septomarginal; 24 - trabeculae carneae; 25 - chordae tendineae; 26 - sinus coronarius; 27 - cuspis ventralis; 28 - cuspis dorsalis; 29 - cuspis septalis; 30 - cuspis post.; 31 - cuspis ant.; 32 - a. coronaria sin.; 33 - a. coronaria dext.