Final answer:
The Purkinje fibers have fast conduction times, roughly 75 ms, and contribute to overall cardiac conduction timing. The blank spaces in the question are likely related to such fibers and their associated conduction rates and intercalated heart transmission times.
Step-by-step explanation:
The student's question pertains to the physiology of cardiac conduction and the timing of electrical impulse transmission through the various components of the heart's electrical system. The Purkinje fibers are specialized conductive fibers that distribute the electrical impulse to the ventricular muscle cells. The impulse transmission through the conduction system, including the SA node, AV node, atrioventricular bundle (Bundle of His), bundle branches, and Purkinje fibers, has different inherent conduction times and intercellular conduction times, known as Intercalated Heart Transmission Times (IHTTs). The SA node initiates impulses that are then slowed at the AV node crucial for heart function, allowing ventricular filling before contraction. Purkinje fibers have a fast conduction rate, transmitting impulses to the ventricles in approximately 75 ms, while continuous conduction along unmyelinated axons is considerably slower due to the distribution of Na+ channels.
The blank spaces in the student's question appear to be looking for details on specific sites in the cardiac conduction system, their conduction times, and IHTTs. The sites with small neuro fibers such as the Purkinje fibers have faster conduction times and shorter IHTTs (approximately 75 ms).