Final answer:
The Purkinje fibers are essential components of the heart's electrical conduction system, responsible for coordinating ventricular contraction by rapidly conducting impulses to the ventricular muscle cells.
Step-by-step explanation:
The subject described is related to the Purkinje fibers, which are specialized myocardial conduction fibers that are part of the heart's electrical conduction system. These fibers spread the impulse to the myocardial contractile cells in the ventricles, ensuring the heart's contraction is coordinated. The Purkinje fibers extend from the apex of the heart toward the atrioventricular septum and base of the heart, and they have a high propriety conduction rate, which allows the impulse to reach all ventricular muscle cells quickly, in approximately 75 ms.
The electrical signals originate from the SA node and cause the atria to contract first. Then, with a slight delay at the AV node, the signals are passed through the bundle of His, then to the left and right bundle branches, and finally, the Purkinje fibers conduct the impulse, causing the ventricles to contract. This process allows the blood to be efficiently pumped out of the ventricles and into the aorta and pulmonary trunk. In the absence of the SA node, the Purkinje fibers can act as a pacemaker with an inherent firing rate of approximately 15-20 impulses per minute.