Conductive system of the heart
Last reviewed: 23.04.2024
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Regulation and coordination of the contractile function of the heart are carried out by its conducting system. The conduction system of the heart is formed by atypical cardiomyocytes (cardiac conducting cardiomyocytes). These cardiomyocytes are richly innervated, have small dimensions (length - about 25 microns, thickness - 10 microns) in comparison with cardiomyocytes of the myocardium.
The cells of the conducting system do not have T-tubes, they are joined together not only by their ends, but also by their lateral surfaces. These cells contain a significant amount of cytoplasm and few myofibrils. The cells of the conducting system have the ability to carry out irritation from the nerves of the heart to the myocardium of the atria and ventricles. The centers of the conduction system of the heart are two nodes:
- sinus-atrial node (the node of the Kisa-Vleck, nodus sinuatrialis) is located in the right atrial wall, between the opening of the superior vena cava and the right ear; gives branches to the myocardium of the atria;
- the atrioventricular node (the Ashot-Tavara node, nodus atrioventricularis) lies in the thickness of the lower part of the interatrial septum. This node goes to the atrioventricular bundle (fasciculus atrioventricularis), which connects the myocardium of the atria with the ventricular myocardium. In the muscular part of the interventricular septum, this bundle is divided into the right and left legs (crus dextrum et crus sinistrum). The terminal branchings of the fibers of the conduction system of the heart (Purkinje fibers), into which these legs disintegrate, terminate in the myocardium on cardiomyocytes of the ventricles.
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