RNSG 2432 - Exam 1 - Module 3: Cardiac Rhythm Disorders|Cardiac Cell Automaticity, Excitability, Conductivity, Contractility, Refractoriness, SA Node, AV Node, Purkinje Fibers, Electrical Conduction, Depolarization, Repolarization, P Wave, PR Interval, QR

RNSG 2432 - Exam 1 - Module 3: Cardiac Rhythm Disorders|Cardiac Cell Automaticity, Excitability, Conductivity, Contractility, Refractoriness, SA Node, AV Node, Purkinje Fibers, Electrical Conduction, Depolarization, Repolarization, P Wave, PR Interval, QRS Complex, ST Segment, T Wave, QT Interval, Normal Sinus Rhythm, Sinus Bradycardia, Sinus Tachycardia, Supraventricular Tachycardia, Atrial Fibrillation, Atrial Flutter, Junctional Rhythm, AV Blocks, Bundle Branch Blocks, Ventricular Tachycardia, Ventricular Fibrillation, Torsades de Pointes, Pulseless Electrical Activity, Asystole, Cardiac Pacemaker, Zoll Pacing Exam Questions Verified and Provided with Complete A+ Graded Rationales Latest Updated 2026 Characteristic of Cardiac Cells •Automaticity- initiate an impulse •Excitability- respond to stimulus •Conductivity- transmit from cell to cell (if some areas blocked can get re-entering impulses- tachycardia) •Contractility- muscle fibers shorten •Refractoriness •Relative •absolute •ability- respond to stimulus •Conductivity- transmit from cell to cell (if some areas blocked can get re-entering impulses- tachycardia •Contractility- muscle fibers shorten •Refractoriness •Relative •absolute Anatomy Physiology Refresher •What is the flow of blood through the heart ? • •What is the electrical conduction of the heart ? • •What is know as the pacemaker of the heart? • •What is Cardiac Output? • •Can the heart rate change CO? Beautifully Built •Did you know that the heart has a backup plan? •SA •AV Purkinje A moment in time • ECG waveforms are produced by the movement of charged ions across the semipermeable membranes of myocardial cells. •Mainly Sodium and Potassium • •What is the role of Calcium • •What labs would we want to know? What am I looking at really? Does Placement matter?? •Lead II negative R arm looking to LL positive- upright P waves and QRS •complex and T wave •(White is right, grass under clouds, smoke above fire) •In 5 lead **V1 is 4th ICS right of sternum - brown or ground (most important) The P wave •Begins with Firing of the SA node •Represents depolarization of the atria. • • Atrium contract and force blood into the ventricles. •Normal Duration-- 0.06-0.12 sec • • •Lewis 770 and 888 PR Interval •Measured from the beginning of the P wave to the beginning of the QRS complex •Represents the length of TIME for the signal to travel. •Normal Duration—0.12-0.20 QRS Electrical Conduction •Q Wave •Not readily seen on all ECG •First negative deflection on QRS complex. •Has substantial meaning if seen. •R Wave •First positive deflection in the Complex •S Wave •Negative deflection after R wave • •Normal Duration 0.12 Sec ST Segment •Measured from the S (in QRS complex) to the beginning of the T wave •Should Be Isoelectric •Normal Duration 0.12