MCCN SDAP X - Med-Surg Exam 1 (EKG)
questions and answers graded A+
SA node - correct answer ✔✔Fires in the atrium at 60-100 bpm
AV node - correct answer ✔✔Fires in the ventricles at 40-60 bpm
Purkinje Fibers - correct answer ✔✔Fire in the ventricular walls at 20-40 bpm
Conduction system of the heart - correct answer ✔✔SA node --> Internodal pathways --> AV
node --> Bundle of His --> Left and Right Bundle Branches --> Purkinje Fibers
Myocardial cells - correct answer ✔✔Produce mechanical function (contractility), measured by
BP and HR
Pacemaker cells - correct answer ✔✔Generate and conduct electrical impulses, measured by
EKG monitor.
Polarization - correct answer ✔✔Resting state, inside of the cell is negatively charged
Depolarization - correct answer ✔✔An electrical event (influx of Na) that causes muscle
contraction
Repolarization - correct answer ✔✔Return to resting state from contraction (outward diffusion
of K)
, P wave - correct answer ✔✔Atrial depolarization/contraction. Impulse originates in SA node, Na
influx.
PR interval - correct answer ✔✔Beginning of the P wave to the beginning of the QRS complex,
usually 0.12-0.20 seconds, greater than 0.20 seconds indicates 1st degree heart block.
Q wave - correct answer ✔✔Pathologic if it is at least 0.04 seconds wide or more than 25% the
total amplitude of the QRS complex; pathologic Q wave is indicative of infarction (cell necrosis).
QRS Complex - correct answer ✔✔Ventricular depolarization/contraction. Impulse originates in
AV node, Na influx. 0.04-0.10 seconds. (Greater than 0.10 seconds is ventricular rate?)
ST segment - correct answer ✔✔Lasts about 0.08 seconds, more than 1mm/small-square
depressed (ischemia) or elevated (active injury, STEMI) is significant and indicates damage to
cardiac muscle. Normal ST is isoelectric.
QT interval - correct answer ✔✔Represents ventricular depolarization and depolarization (Na
influx and K efflux), usually less than half R-R interval, and 0.32-0.40 seconds when HR is 65-90
bpm. Prolonged QT = risk for rapid abnormal heart rhythm (e.g. V-tach)
T wave - correct answer ✔✔Ventricular repolarization, K outflow. T wave inversion indicates
ischemia.
Isoelectric line - correct answer ✔✔No electrical activity
EKG paper - correct answer ✔✔Small square (1mm) = 0.1mv and 0.04 sec
Large square (5mm) = 0.5mv and 0.2 sec (5x5 small squares)
questions and answers graded A+
SA node - correct answer ✔✔Fires in the atrium at 60-100 bpm
AV node - correct answer ✔✔Fires in the ventricles at 40-60 bpm
Purkinje Fibers - correct answer ✔✔Fire in the ventricular walls at 20-40 bpm
Conduction system of the heart - correct answer ✔✔SA node --> Internodal pathways --> AV
node --> Bundle of His --> Left and Right Bundle Branches --> Purkinje Fibers
Myocardial cells - correct answer ✔✔Produce mechanical function (contractility), measured by
BP and HR
Pacemaker cells - correct answer ✔✔Generate and conduct electrical impulses, measured by
EKG monitor.
Polarization - correct answer ✔✔Resting state, inside of the cell is negatively charged
Depolarization - correct answer ✔✔An electrical event (influx of Na) that causes muscle
contraction
Repolarization - correct answer ✔✔Return to resting state from contraction (outward diffusion
of K)
, P wave - correct answer ✔✔Atrial depolarization/contraction. Impulse originates in SA node, Na
influx.
PR interval - correct answer ✔✔Beginning of the P wave to the beginning of the QRS complex,
usually 0.12-0.20 seconds, greater than 0.20 seconds indicates 1st degree heart block.
Q wave - correct answer ✔✔Pathologic if it is at least 0.04 seconds wide or more than 25% the
total amplitude of the QRS complex; pathologic Q wave is indicative of infarction (cell necrosis).
QRS Complex - correct answer ✔✔Ventricular depolarization/contraction. Impulse originates in
AV node, Na influx. 0.04-0.10 seconds. (Greater than 0.10 seconds is ventricular rate?)
ST segment - correct answer ✔✔Lasts about 0.08 seconds, more than 1mm/small-square
depressed (ischemia) or elevated (active injury, STEMI) is significant and indicates damage to
cardiac muscle. Normal ST is isoelectric.
QT interval - correct answer ✔✔Represents ventricular depolarization and depolarization (Na
influx and K efflux), usually less than half R-R interval, and 0.32-0.40 seconds when HR is 65-90
bpm. Prolonged QT = risk for rapid abnormal heart rhythm (e.g. V-tach)
T wave - correct answer ✔✔Ventricular repolarization, K outflow. T wave inversion indicates
ischemia.
Isoelectric line - correct answer ✔✔No electrical activity
EKG paper - correct answer ✔✔Small square (1mm) = 0.1mv and 0.04 sec
Large square (5mm) = 0.5mv and 0.2 sec (5x5 small squares)
