Basic Electrophysiology
Chapter 02:
Basic Electrophysiology Aehlert:
ECGs Made Easy, 6th Edition
MULTIPLE CHOICE
1. In most patients, the sinoatrial (SA) and atrioventricular (AV) nodes are supplied by the
coronary artery.
a. right
b. left main
c. circumflex
d. left anterior descending
ANSWER: A
The SA node receives its blood supply from the SA node artery that runs lengthwise through
the center of the node. The SA node artery originates from the right coronary artery in about
60% of people. The AV node is supplied by the right coronary artery in 85% to 90% of the
population. In the remainder, the circumflex artery provides the blood supply.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
2. The intrinsic rate of the atrioventricular (AV) bundle is beats/min.
a. 20 to 40
b. 40 to 60
c. 60 to 80
d. 80 to 100
ANSWER: B
The AV bundle has pacemaker cells capable of firing at a rate of 40 to 60 beats/min.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
3. How do you determine whether the atrial rhythm on an ECG tracing is regular or irregular?
a. Compare QT intervals.
b. Compare PR intervals.
c. Compare R to R intervals.
d. Compare P to P intervals.
ANSWER: D
To evaluate the regularity of the atrial rhythm on a rhythm strip, the interval between two
consecutive P waves is measured. The distance between succeeding P-P intervals is measured
and compared. If the atrial rhythm is regular, the P-P intervals will measure the same.
OBJ: Describe a systematic approach to the analysis and interpretation of cardiac dysrhythmias.
4. is the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse
without being stimulated from another source, such as a nerve.
a. Excitability
b. Conductivity
c. Automaticity
1
, Basic Electrophysiology
d. Contractility
ANSWER: C
The ability of cardiac pacemaker cells to create an electrical impulse without being stimulated
from another source is called automaticity. Excitability is the heart muscles’ ability to respond
to impulse or stimulus. Conductivity is the ability of the cardiac cells to receive and
trANSWERmit an electrical impulse. Contractility is the contraction of the heart muscle
which produces the heartbeat.
OBJ: Describe the primary characteristics of cardiac cells.
5. In the heart’s conduction system, the receive(s) an electrical impulse from the bundle
of His and relay(s) it to the Purkinje fibers in the ventricular myocardium.
a. atrioventricular (AV) node
b. atria
c. sinoatrial (SA) node
d. right and left bundle branches
ANSWER: D
The right and left bundle branches divide into smaller and smaller branches and then into a
special network of fibers called the Purkinje fibers. These fibers spread from the
interventricular septum into the papillary muscles. They continue downward to the apex of the
heart, composing an elaborate web that penetrates about one third of the way into the
ventricular muscle mass. The fibers then become continuous with the muscle cells of the right
and left ventricles.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
6. In the heart’s conduction system, the receive(s) an electrical impulse from the right and
left bundle branches and relay(s) it to the ventricular myocardium.
a. AV node
b. SA node
c. Purkinje fibers
d. atrial pacemaker cells
ANSWER: C
The right bundle branch innervates the right ventricle. The left bundle branch spreads the
electrical impulse to the interventricular septum and left ventricle.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
7. What does the QRS complex represent?
a. Atrial depolarization
b. Ventricular contraction
c. Ventricular repolarization
d. Ventricular depolarization
ANSWER: D
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Chapter 02:
Basic Electrophysiology Aehlert:
ECGs Made Easy, 6th Edition
MULTIPLE CHOICE
1. In most patients, the sinoatrial (SA) and atrioventricular (AV) nodes are supplied by the
coronary artery.
a. right
b. left main
c. circumflex
d. left anterior descending
ANSWER: A
The SA node receives its blood supply from the SA node artery that runs lengthwise through
the center of the node. The SA node artery originates from the right coronary artery in about
60% of people. The AV node is supplied by the right coronary artery in 85% to 90% of the
population. In the remainder, the circumflex artery provides the blood supply.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
2. The intrinsic rate of the atrioventricular (AV) bundle is beats/min.
a. 20 to 40
b. 40 to 60
c. 60 to 80
d. 80 to 100
ANSWER: B
The AV bundle has pacemaker cells capable of firing at a rate of 40 to 60 beats/min.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
3. How do you determine whether the atrial rhythm on an ECG tracing is regular or irregular?
a. Compare QT intervals.
b. Compare PR intervals.
c. Compare R to R intervals.
d. Compare P to P intervals.
ANSWER: D
To evaluate the regularity of the atrial rhythm on a rhythm strip, the interval between two
consecutive P waves is measured. The distance between succeeding P-P intervals is measured
and compared. If the atrial rhythm is regular, the P-P intervals will measure the same.
OBJ: Describe a systematic approach to the analysis and interpretation of cardiac dysrhythmias.
4. is the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse
without being stimulated from another source, such as a nerve.
a. Excitability
b. Conductivity
c. Automaticity
1
, Basic Electrophysiology
d. Contractility
ANSWER: C
The ability of cardiac pacemaker cells to create an electrical impulse without being stimulated
from another source is called automaticity. Excitability is the heart muscles’ ability to respond
to impulse or stimulus. Conductivity is the ability of the cardiac cells to receive and
trANSWERmit an electrical impulse. Contractility is the contraction of the heart muscle
which produces the heartbeat.
OBJ: Describe the primary characteristics of cardiac cells.
5. In the heart’s conduction system, the receive(s) an electrical impulse from the bundle
of His and relay(s) it to the Purkinje fibers in the ventricular myocardium.
a. atrioventricular (AV) node
b. atria
c. sinoatrial (SA) node
d. right and left bundle branches
ANSWER: D
The right and left bundle branches divide into smaller and smaller branches and then into a
special network of fibers called the Purkinje fibers. These fibers spread from the
interventricular septum into the papillary muscles. They continue downward to the apex of the
heart, composing an elaborate web that penetrates about one third of the way into the
ventricular muscle mass. The fibers then become continuous with the muscle cells of the right
and left ventricles.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
6. In the heart’s conduction system, the receive(s) an electrical impulse from the right and
left bundle branches and relay(s) it to the ventricular myocardium.
a. AV node
b. SA node
c. Purkinje fibers
d. atrial pacemaker cells
ANSWER: C
The right bundle branch innervates the right ventricle. The left bundle branch spreads the
electrical impulse to the interventricular septum and left ventricle.
OBJ: Describe the location, function, and, when appropriate, the intrinsic rate of the following
structures: sinoatrial node, atrioventricular bundle, and Purkinje fibers.
7. What does the QRS complex represent?
a. Atrial depolarization
b. Ventricular contraction
c. Ventricular repolarization
d. Ventricular depolarization
ANSWER: D
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