Purkinjesäikeisiin

Purkinjesäikeisiin, also known as Purkinje fibers, are specialized cardiac muscle cells that form part of the electrical conduction system of the heart. These fibers are found in the endocardium, the innermost layer of the heart wall. They are responsible for rapidly transmitting the electrical impulse from the atrioventricular (AV) node to the ventricles, triggering their coordinated contraction.

The Purkinje fiber network originates from the bundle of His, which branches into a right and left bundle branch. These branches then further subdivide into a vast network of Purkinje fibers that spread throughout the ventricular myocardium. Unlike typical cardiac muscle cells (myocytes), Purkinje fibers have fewer myofibrils, making them appear paler under a microscope. They are larger in diameter and contain more sarcoplasm. This structural adaptation facilitates the rapid conduction of electrical impulses.

The speed at which the electrical signal travels through the Purkinje fibers is significantly faster than in the regular ventricular muscle. This rapid conduction ensures that the ventricles contract simultaneously, allowing for efficient pumping of blood. Any disruption in the function or integrity of the Purkinje fiber system can lead to serious cardiac arrhythmias, such as heart block or ventricular tachycardia. Therefore, understanding the role and structure of Purkinje fibers is crucial in the study of cardiac electrophysiology and the diagnosis of heart conditions.