UCLA EKG test

electrically polarized at rest - inside of heart cell has a high potassium concentration, whereas the outside has a higher concentration of NA -higher positive charge outside the cell cause more negative charge inside cell electrical potential difference between the charges outside and inside of the cell wall Brainpower Read More 0:09 / 0:15 Depolarization NA moves into the cell rapidly in response to an electrical impulse - inside cell loses negative potential Replolarization ions return to their original resting state - heart cells restore their resting polarity 4 Phases of Electrophysiology of the heart cell Phase 0: Na flow in and rapid depolarization occurs when stimulated Phase 1: Rapid return to isoelectric level Phase 2: CA ions flow in and myocytes contract Phase 3: K flow out and rapid depolarization occurs Phase 4: Polarized resting phase Pacemaker cells - Sinoatrial node ( SA) node -Atrioventricular node )AV node - Purkinjie fibers SA node -primary pacemaker -