Purkinjeszálak

Purkinje fibers are specialized cardiac muscle cells that form part of the electrical conduction system of the heart. They are named after the Czech physician Jan Evangelista Purkyně, who first described them in 1839. These fibers are responsible for rapidly transmitting the electrical impulse from the bundle of His to the ventricular myocardium, ensuring a coordinated contraction of the ventricles.

Originating from the bundle branches, Purkinje fibers are characterized by their large diameter, pale cytoplasm, and sparse myofibrils compared to contractile cardiac muscle cells. This structural adaptation allows for faster conduction of electrical signals. They are typically found just beneath the endocardium, the inner lining of the ventricles.

The electrical impulse generated by the sinoatrial (SA) node travels through the atria, reaches the atrioventricular (AV) node, and then passes to the bundle of His. The bundle of His divides into the left and right bundle branches, which further subdivide into the Purkinje fibers. These fibers then distribute the impulse throughout the ventricular walls, causing them to contract and pump blood out of the heart. The rapid conduction through Purkinje fibers is crucial for efficient ventricular filling and ejection. Any abnormalities in the Purkinje fiber system can lead to various cardiac arrhythmias.