Cardiac Dysrhythmias complete verified exam 2025 Part One with accurate expert curated solutions ( 100% ACCURACY )

Car diac Dysr hythm ias com plete
ver ifi ed exam 2025 Par t One
w ith accur ate exper t cur ated
solutions ( 100% ACCURACY )
Cardiac Dysrhythmias: Electrical Conduction System
Multiple Choice Test
1. What is the primary pacemaker of the heart?
a) Atrioventricular (AV) node

,b) Sinoatrial (SA) node
c) Bundle of His
d) Purkinje fibers
Answer: b) Sinoatrial (SA) node
Explanation: The SA node is the primary pacemaker of the heart,
initiating the heartbeat.
2. What is the normal rate of automaticity for the SA node?
a) 40 – 60 bpm
b) 20 – 40 bpm
c) 60 – 100 bpm
d) 100 – 120 bpmAnswer: c) 60 – 100 bpm
Explanation: The SA node typically fires at a rate of 60 to 100 beats per
minute.
3. Where is the SA node located?
a) Right atrium
b) Left ventricle
c) Right ventricle
d) Left atrium
Answer: a) Right atrium
Explanation: The SA node is situated in the right atrium of the heart.
4. Which node is considered the secondary pacemaker of the heart?
a) Sinoatrial (SA) node
b) Atrioventricular (AV) node
c) Bundle of His
d) Purkinje fibers
Answer: b) Atrioventricular (AV) node
Explanation: The AV node acts as the secondary pacemaker when the
SA node fails.
5. What is the normal rate of automaticity for the Atrioventricular (AV)
node?
a) 60 – 100 bpm

,b) 40 – 60 bpm
c) 20 – 40 bpm
d) 100 – 120 bpm
Answer: b) 40 – 60 bpm
Explanation: The AV node fires at a rate of 40 to 60 beats per minute.
6. What happens if both the SA and AV nodes fail to generate an
impulse?
a) The atria stop contracting
b) The Bundle of His takes over
c) The Purkinje fibers take over as pacemaker
d) The heart ceases to function
Answer: c) The Purkinje fibers take over as pacemaker
Explanation: If both the SA and AV nodes fail, the Purkinje fibers act as a
last resort pacemaker with a rate of 20–40 bpm.
7. Which of the following has the fastest rate of automaticity?
a) SA node
b) AV node
c) Bundle of His
d) Purkinje fibers
Answer: a) SA node
Explanation: The SA node has the fastest intrinsic rate of automaticity,
between 60-100 bpm.
8. Which part of the heart's electrical conduction system has the
slowest intrinsic firing rate? a) SA node
b) AV node
c) Purkinje fibers
d) Bundle of His
Answer: c) Purkinje fibers
Explanation: The Purkinje fibers fire at a rate of 20–40 bpm, the slowest
in the conduction system.

, 9. Which of the following describes the location and function of the
Bundle of His?
a) Located in the right atrium; primary pacemaker
b) Located between the atria and ventricles; conducts impulses to the
ventricles
c) Located in the ventricles; initiates contraction of the ventricles
d) Located in the left atrium; slows down the heart rate
Answer: b) Located between the atria and ventricles; conducts
impulses to the ventricles
Explanation: The Bundle of His transmits electrical impulses from the AV
node to the ventricles.
10. What role do the Purkinje fibers play in the heart's conduction
system?
a) They slow down the heart rate.
b) They initiate electrical impulses in the SA node.
c) They conduct electrical impulses to the ventricular myocardium,
causing contraction.
d) They generate electrical impulses that override the SA node.Answer:
c) They conduct electrical impulses to the ventricular myocardium,
causing contraction
Explanation: Purkinje fibers ensure that the ventricles contract in
coordination to pump blood effectively.
11. Which part of the heart is most responsible for the delay in
electrical conduction, allowing the ventricles time to fill with blood?
a) SA node
b) AV node
c) Bundle of His
d) Purkinje fibers
Answer: b) AV node
Explanation: The AV node slows down the electrical impulse to allow
the ventricles time to fill before contraction.