What Is the Cardiac Conduction System?
The cardiac conduction system is composed of special myocardial cells that can generate and conduct impulses in the myocardium, including sinoatrial nodes, internode bundles, atrioventricular nodes, atrioventricular bundles, right bundle branch, and Purkinje fibers. The sinoatrial node is the pacing point for normal heart rate, and is located below the epicardium between the entrance of the superior vena cava and the right atrial appendage; the internode bundle is the conduction pathway between the sinoatrial node and the atrioventricular node and is divided into the anterior node bundle There are three conducting beams in the middle and posterior node bundles, among which the anterior node bundle sends a branch to the left atrium called the room bundle. The atrioventricular node is located below the right endocardium of the atrioventricular septum, lying horizontally in the area between the coronary sinus ostium, the oval fossa, and the upper edge of the tricuspid valve septum, extending downward into the atrioventricular bundle. The atrioventricular node and the atrioventricular bundle (His bundle) constitute the atrioventricular junction area, and then extend forward and down to the lower end of the interventricular septum, divided into left and right bundle branches, which are respectively located below the left and right endocardium of the septal branch. At the beginning of the left side of the ventricular septum, it is divided into two bundles of anterior and superior branches; the right bundle branch descends along the right side of the ventricular septum and does not branch into Purkinje fibers until the apex. The right bundle branch is connected to Purkinje fiber network under the endocardium, and finally to the ventricular muscle. [1]
Cardiac conduction system
Right!
- The cardiac conduction system is composed of special myocardial cells that can generate and conduct impulses in the myocardium, including sinoatrial nodes, internode bundles, atrioventricular nodes, atrioventricular bundles, right bundle branch, and Purkinje fibers. The sinoatrial node is the pacing point for normal heart rate, and is located below the epicardium between the entrance of the superior vena cava and the right atrial appendage; the internode bundle is the conduction pathway between the sinoatrial node and the atrioventricular node and is divided into the anterior node bundle There are three conducting beams in the middle and posterior node bundles, among which the anterior node bundle sends a branch to the left atrium called the room bundle. The atrioventricular node is located below the right endocardium of the atrioventricular septum, lying horizontally in the area between the coronary sinus ostium, the oval fossa, and the upper edge of the tricuspid valve septum, extending downward into the atrioventricular bundle. The atrioventricular node and the atrioventricular bundle (His bundle) constitute the atrioventricular junction area, and then extend forward and down to the lower end of the interventricular septum, divided into left and right bundle branches, which are respectively located below the left and right endocardium of the septal branch. At the beginning of the left side of the ventricular septum, it is divided into two bundles of anterior and superior branches; the right bundle branch descends along the right side of the ventricular septum and does not branch into Purkinje fibers until the apex. The right bundle branch is connected to Purkinje fiber network under the endocardium, and finally to the ventricular muscle. [1]
- The function of the cardiac conduction system is to generate impulses and conduct them to various parts of the heart, so that the atrial and ventricular muscles contract according to a certain rhythm.
- 1) The conduction system of the heart includes the sinoatrial node, the atrioventricular node, the atrioventricular bundle, the branches of the left and right atrioventricular bundle, and many thin branches distributed to the ventricular papillary muscles and the ventricular wall.
- 2) Except for the sinoatrial node located deep in the right atrium and the epicardium, the rest are distributed in the subendocardium.
- 3) There are three types of special myocardial fibers that make up the cardiac conduction system: pacing cells (participating in the sinoatrial node and atrioventricular node), transitional cells (acting as conduction impulses), and Purkinje fibers (immediately transmitting impulses) ).
- 4) Purkinje fibers at the end of the branch of the atrioventricular bundle are connected to the ventricular muscles.
- 5) The function of the cardiac conduction system is to generate and conduct impulses to maintain the rhythmic beat of the heart.
- The schematic diagram of the cardiac conduction system is as follows: