A-V bundle fibers are smaller in diameter than other Purkinjee fibers which slows impulse down and allows emptying of atria before contraction of ventricles. Conduction fibers are continued from the A-V bundle in the wall dividing to form the right and left bundle branches to supply the right and left ventricles. Cardiac muscle contracts more slowly than skeletal muscle and the refractory period is longer. Both atria contract at the same time and both ventricles contract at the same time. Contraction of muscle fibers within a syncytis is synchronized.
Defibrillation causes simultaneous depolarization of all Cardiac muscle fibers.
Cardiac Cycle Refers to the sequence of events that occurs during one complete heartbeat. Diastole refers to relaxation of a heart chamber before and during filling of the chamber Systole refers to contraction of a heart chamber in the process of emptying. Recording of electrical activity of the heart. ECG is altered when heart muscle is damaged or ventricle walls are thickened. T wave represents ventricular repolarization When viewing an electrocardiogram, it can be seen that deflections of the waves whether positive or negative occur occur from a common line known as the isoelectric line.