Anatomical structure of the human heart
The heart is the main organ of the circulatory system. The anatomical structure of the human heart is such that it fully ensures the performance of the functions of the central organ of the blood supply system of the whole organism.
This organ is located in the chest cavity: behind the sternum in the anterior mediastinum above the diaphragm. 70% of the heart is located in the thoracic cavity on the left, 30% - to the right of the sternum. Consider the structure of the human heart, starting with its wall. The cardiac wall has a three-layered structure: the inner layer is the endocardium lined with endotheliocytes; middle - muscle or myocardium, consisting of cardiomyocytes; outer - epicardium and pericardium, formed by a thin shell of connective tissue, the inner surface of which is covered with mesothelium. All cavities of the body from the inside are sent by the endocardium, it also forms heart valves. A pericardium, sometimes called a heart-shaped shirt, covers it from the outside and forms a so-called heart bag. Its main purpose is to reduce the friction of the heart while working and protect it from external influences. Between the leaves of the pericardium there is a slicate space filled with a small volume of fluid.
The heart is divided by a partition into two hollowhalf - left and right. Each half consists of the atrium and the ventricle. In the right half there is always venous blood, in the left - the arterial blood. The structure of the human heart is such that the venous blood never mixes with the arterial blood. Between the right chambers is a tricuspid valve, at the exit point from the right ventricle of the pulmonary artery - the pulmonary valve. In the left half of the heart between the atrium and the ventricle is a bivalve or mitral valve, and at the exit of the aorta from the left ventricular cavity is the tricuspid valve of the aorta with half-moon leaflets. The thickness of the wall of the left ventricle is much larger than in the right ventricle. This is because the left ventricle always works more intensively, throwing blood into the aorta, which then goes on throughout the body, and the right one - only in the vessels of the lungs.
In the right atrium carry the blood of two large veins,which are called the upper and lower hollow. They collect venous blood from all organs. The left atrium receives blood from four pulmonary veins, which, after enriching with oxygen in the lungs, becomes arterial. The pulmonary artery, called the pulmonary trunk, along which the venous blood goes to the lungs, exits the right ventricle. The largest artery of the aorta supplies the entire body with arterial blood, it leaves the left ventricle. From all of the above, we can conclude that the structure of the human heart is no different from the hearts of other mammals.
The heart itself receives blood from two coronaryarteries. The left coronary artery originates in the left aortic sinus or the left sinus of Valsalva, located 1 cm above the place of attachment of the semilunar valves. It branches into the anterior interventricular and envelope branches, supplying the anterolateral blood and part of the posterior wall of the left ventricle, as well as part of the interventricular septum, the apex of the heart and the left atrium. From the right sinus of the aorta or right sinus of Valsalva, the right coronary artery begins. This vessel delivers blood to the myocardium of the right atrium and right ventricle, a small part of the interventricular septum.
The heart of man, whose structure we areconsidered, performs the functions of automatism, conductivity, excitability and contractility. The work of this body is guided by cardiac centers located in the medulla oblongata and bridge. They affect the heart rate, the rate of atrioventricular conduction, the force of the heartbeats.
The physiology of the heart of man is such that histhe vital activity consists in constantly alternating contractions and relaxations, that is, systoles and diastoles that ensure the movement of blood, and with it the continuous supply of oxygen and nutrition to all cells of the body.