CVP Exam & Eval Study Guide: 2025/2026 Syllabus
How to Use This Guide: Test your knowledge by attempting to answer the question
before looking at the provided answer. The format is designed for quick review and self-
assessment.
Section 1: Electrophysiology of the Heart
1. What is the primary pacemaker of the heart and what is its intrinsic firing rate?
ANSWER ✓ The primary pacemaker is the Sinoatrial (SA) node. Its intrinsic firing rate is
60-100 beats per minute.
2. What property of cardiac cells allows the SA node to spontaneously generate
action potentials?
ANSWER ✓ The property is known as automaticity or pacemaker activity.
3. Describe the phase of the SA node action potential that is responsible for its
automaticity.
ANSWER ✓ It is Phase 4, the spontaneous diastolic depolarization, where the membrane
potential gradually becomes less negative until it reaches the threshold for a new action
potential.
4. Which ion channels are primarily responsible for the Phase 4 depolarization in
the SA node?
ANSWER ✓ The "funny" current (I-f channels), which are permeable to Na+ and K+, and
T-type Calcium channels.
5. What is the role of the Atrioventricular (AV) node in cardiac conduction?
ANSWER ✓ The AV node delays the impulse from the atria to the ventricles, allowing for
complete atrial emptying before ventricular contraction. Its intrinsic rate is 40-60 beats
per minute.
6. Why is the slow conduction velocity of the AV node functionally important?
, ANSWER ✓ The slow conduction ensures a critical delay (approximately 0.1 seconds)
that allows the atria to contract and fully eject blood into the ventricles before
ventricular systole begins.
7. What are the Purkinje fibers and what is their intrinsic firing rate?
ANSWER ✓ Purkinje fibers are specialized, fast-conducting cardiac fibers that rapidly
transmit the electrical impulse through the ventricular myocardium. Their intrinsic rate is
15-40 beats per minute.
8. Define the absolute refractory period in a cardiac myocyte.
ANSWER ✓ It is the period during which no stimulus, no matter how strong, can elicit
another action potential. This prevents tetanic contraction and allows the heart to refill.
9. How does the ventricular myocyte action potential differ from the SA node
action potential?
ANSWER ✓ Ventricular myocytes have a stable resting potential (Phase 4), a very rapid
upstroke (Phase 0) due to fast Na+ channels, and a long plateau (Phase 2) due to Ca2+
influx, which is absent in SA node cells.
10. What is the "pacemaker potential" and where does it occur?
ANSWER ✓ The pacemaker potential is the spontaneous, gradual depolarization of the
membrane potential during Phase 4 in autorhythmic cells like those in the SA and AV
nodes.
11. What effect does sympathetic nervous system stimulation have on heart rate?
ANSWER ✓ Sympathetic stimulation releases norepinephrine, which increases the slope
of Phase 4 depolarization, thereby increasing heart rate (positive chronotropy).
12. What effect does parasympathetic (vagal) stimulation have on heart rate?
ANSWER ✓ Parasympathetic stimulation releases acetylcholine, which decreases the
slope of Phase 4 depolarization and hyperpolarizes the SA node, thereby decreasing
heart rate (negative chronotropy).
13. What is an ectopic pacemaker?
ANSWER ✓ An ectopic pacemaker is any pacemaker site other than the normal SA node
that initiates a heartbeat, potentially causing arrhythmias.
How to Use This Guide: Test your knowledge by attempting to answer the question
before looking at the provided answer. The format is designed for quick review and self-
assessment.
Section 1: Electrophysiology of the Heart
1. What is the primary pacemaker of the heart and what is its intrinsic firing rate?
ANSWER ✓ The primary pacemaker is the Sinoatrial (SA) node. Its intrinsic firing rate is
60-100 beats per minute.
2. What property of cardiac cells allows the SA node to spontaneously generate
action potentials?
ANSWER ✓ The property is known as automaticity or pacemaker activity.
3. Describe the phase of the SA node action potential that is responsible for its
automaticity.
ANSWER ✓ It is Phase 4, the spontaneous diastolic depolarization, where the membrane
potential gradually becomes less negative until it reaches the threshold for a new action
potential.
4. Which ion channels are primarily responsible for the Phase 4 depolarization in
the SA node?
ANSWER ✓ The "funny" current (I-f channels), which are permeable to Na+ and K+, and
T-type Calcium channels.
5. What is the role of the Atrioventricular (AV) node in cardiac conduction?
ANSWER ✓ The AV node delays the impulse from the atria to the ventricles, allowing for
complete atrial emptying before ventricular contraction. Its intrinsic rate is 40-60 beats
per minute.
6. Why is the slow conduction velocity of the AV node functionally important?
, ANSWER ✓ The slow conduction ensures a critical delay (approximately 0.1 seconds)
that allows the atria to contract and fully eject blood into the ventricles before
ventricular systole begins.
7. What are the Purkinje fibers and what is their intrinsic firing rate?
ANSWER ✓ Purkinje fibers are specialized, fast-conducting cardiac fibers that rapidly
transmit the electrical impulse through the ventricular myocardium. Their intrinsic rate is
15-40 beats per minute.
8. Define the absolute refractory period in a cardiac myocyte.
ANSWER ✓ It is the period during which no stimulus, no matter how strong, can elicit
another action potential. This prevents tetanic contraction and allows the heart to refill.
9. How does the ventricular myocyte action potential differ from the SA node
action potential?
ANSWER ✓ Ventricular myocytes have a stable resting potential (Phase 4), a very rapid
upstroke (Phase 0) due to fast Na+ channels, and a long plateau (Phase 2) due to Ca2+
influx, which is absent in SA node cells.
10. What is the "pacemaker potential" and where does it occur?
ANSWER ✓ The pacemaker potential is the spontaneous, gradual depolarization of the
membrane potential during Phase 4 in autorhythmic cells like those in the SA and AV
nodes.
11. What effect does sympathetic nervous system stimulation have on heart rate?
ANSWER ✓ Sympathetic stimulation releases norepinephrine, which increases the slope
of Phase 4 depolarization, thereby increasing heart rate (positive chronotropy).
12. What effect does parasympathetic (vagal) stimulation have on heart rate?
ANSWER ✓ Parasympathetic stimulation releases acetylcholine, which decreases the
slope of Phase 4 depolarization and hyperpolarizes the SA node, thereby decreasing
heart rate (negative chronotropy).
13. What is an ectopic pacemaker?
ANSWER ✓ An ectopic pacemaker is any pacemaker site other than the normal SA node
that initiates a heartbeat, potentially causing arrhythmias.
