EKG Test Study Questions and Answers

What cells cause the heart to contract? Contractile cells What creates and conducts impulses to regulate the cardiac cycle? Conduction system cells What controls involuntary bodily functions and has two subdivisions? Autonomic nervous system Sympathetic nervous system Fight or flight. Hits the accelerator. How does depolarization occur? Change in the cardiac cell's electrical charge from negative to positive. Accomplished by sodium and potassium ions changing place. Causes a wave of electrical to course from cell to cell, resulting in a discharge of electricity. How does repolarization occur? Return of the cardiac cell to its electrically negative charge. Accomplished by way of the Na+ K+ pump, an active transport system. Depolarization should result in? Heart muscle contraction Repolarization should result in? Heart muscle relaxation Phase 4 Cardiac cell at rest Phase 0 Depolarization Phases 1 & 2 Early repolarization Phase 2 Plateau phase Phase 3 Rapid repolarization Absolute refractory No stimulus can cause depolarization Relative refractory Strong stimulus can cause depolarization Supernormal period Even a weak stimulus can cause depolarization