Final answer:
Purkinje fibers spread from the bundle branches throughout the ventricular myocardium, from the apex to the base of the heart, ensuring rapid and coordinated contraction of the ventricles. They originate from the bifurcation of the atrioventricular bundle into the right and left bundle branches which further connect to the Purkinje fibers. The Purkinje fibers are essential for the proper cardiac cycle, and if they are blocked, it would disrupt the heart's normal rhythm.
Step-by-step explanation:
Where Do Purkinje Fibers Spread:
The Purkinje fibers are specialized myocardial conduction fibers that play a critical role in the heart's electrical system. They arise from the left and right bundle branches and extend through the myocardium, from the apex of the heart towards the atrioventricular septum and the base of the heart. These fibers ensure that the electrical impulse for myocardial contraction spreads rapidly to the ventricular muscle cells. The impulse travels from the atrioventricular bundle through the bundle branches and finally reaches the Purkinje fibers, which in turn stimulate the ventricular muscle cells to contract. This process ensures that blood is pumped efficiently from the ventricles into the aorta and the pulmonary trunk.
The atrioventricular bundle branches serve as the pathway for the electrical signals from the atrioventricular node, splitting into the left and right branches to supply the corresponding ventricles. The left bundle branch is larger due to the greater size of the left ventricle. A special feature on the right side is the moderator band, which carries a portion of the right bundle branch to supply the right papillary muscles, allowing for synchronized contraction with the ventricular myocardium. During the cardiac cycle, if neural signals were blocked within the Purkinje fibers, the heart's ability to coordinate the contraction of ventricular muscle cells would be severely impaired, affecting the cardiac cycle and potentially leading to arrhythmias or cardiac dysfunction.