The heart is a hollow muscular organ, where, without mixing of blood, the large (systemic) circle of blood circulation intersects with the small pulmonary. For this reason, it is called the central organ of the cardiovascular system. Blood flows to its right sections through the vena cava, which, after entering the right ventricle, the pulmonary trunk diverts to the lungs. From them, blood is diverted to the left atrium through 4 pulmonary veins, and from the ventricle to the periphery it is sent by the aorta.
Cardiac Anatomy
The heart is a hollow organ, the bulk of which is the myocardium, consisting of myocytes and pacemakers. The heart muscle forms a "bag" with four cavities: two atria and two ventricles. The right atrial cavity receives venous blood supplied to it from the systemic circulation and directs it through the atrioventricular outflow tract to the ventricle. Its wallthin, only about 3-4 mm, and the pressure in the cavity is much lower than in the left ventricle (LV).
The atria of the heart fill with blood at the time of ventricular diastole, and then the blood enters the ventricles on its own, although there is still a slight atrial systole at the end of diastolic filling. In a fraction of a second, in ventricular systole, this blood will be directed to the pulmonary trunk and aorta.
Valve apparatus
To prevent the backflow of blood into the atrial cavities and its retention in the ventricles, the valve apparatus is developed in the heart. Heart valves are derivatives of connective tissue that block intracardiac regurgitation. The cavity of the right atrium and ventricle closes the tricuspid (right AV-) valve. The reverse flow of blood into the cavity of the right ventricle prevents the tricuspid valve of the pulmonary trunk.
On the anatomical border of the left atrium and ventricle is the mitral valve, which consists of only two cusps. Blood is carried from the left ventricle through the aortic tract to the aorta, the largest artery in the body, capable of withstanding high hydrostatic pressure and transmitting a pulse wave. There is a massive aortic valve in this area.
Different vessels of the heart
The aorta and pulmonary trunk are arterial vessels that carry blood away from the heart. Through the aorta, oxygenated blood enters the systemic peripheral circulation, and through the pulmonary trunk into the lungs to the site of saturation of venous blood with oxygen. The pulmonary trunk isthe only artery in an adult that carries venous blood containing a small amount of oxygen.
Conversely, the 4 pulmonary veins that drain into the left atrium are the only venous vessels in the adult body that carry oxygenated arterial blood. In a he althy person, venous and arterial blood do not mix, as they fill different cavities of the heart.
Pulmonary trunk
This blood vessel is the beginning of the pulmonary circulation. The pulmonary trunk supplies venous blood to the lungs under low hydrostatic pressure from the right ventricle. Its diameter reaches 3 cm. The valve of the pulmonary trunk consists of 3 flaps at the mouth, from where the vessel goes up and to the left, in front of the aorta. It then goes around the aortic vessel on the left and divides into 2 short pulmonary arteries at the level of the 4th thoracic vertebra.
The right pulmonary artery (LA), heading towards the corresponding lung, is located behind the ascending aorta and vena cava. The left LA is in front of the descending aorta. At the gates of the lungs, they divide into lobar branches, and then into small arteries, arterioles, precapillaries and capillaries. With their help, venous blood is delivered to the air-blood barrier at the level of the smallest vessels, where oxygenation will occur.
