Cardiac Electrophysiology: Master the Heart's Electrical Activity

Question 1

Which phase of the cardiac action potential is characterized by calcium influx through L-type calcium channels?

Accepted Answer

Phase 0

Answer

Phase 1

Answer

Phase 2

Answer

Phase 3

Question 2

What is the main ion responsible for the rapid upstroke of the cardiac action potential?

Accepted Answer

Sodium

Answer

Potassium

Answer

Calcium

Answer

Chloride

Question 3

What is the typical ECG finding associated with hyperkalemia?

Accepted Answer

Peaked T waves

Answer

Prolonged PR interval

Answer

QRS widening

Answer

ST segment depression

Question 4

Which ion channel is responsible for the delayed rectifier potassium current (IKr)?

Accepted Answer

Kv11.1

Answer

Kv1.5

Answer

Kv4.3

Answer

Nav1.5

Question 5

What is the primary mechanism of action of most antiarrhythmic drugs?

Accepted Answer

Blocking ion channels

Answer

Increasing sympathetic activity

Answer

Reducing parasympathetic activity

Answer

Stimulating hormone secretion

Question 6

Which of the following arrhythmias is characterized by a ventricular rate between 150-250 bpm?

Accepted Answer

Ventricular tachycardia

Answer

Sinus tachycardia

Answer

Atrial fibrillation

Answer

Bradycardia

Question 7

Which of the following techniques is used to record the electrical activity of the esophagus?

Accepted Answer

Esophageal manometry

Answer

Electrocardiography

Answer

Electrogastrography

Answer

Polysomnography

Question 8

What is the significance of the sinoatrial node in cardiac electrophysiology?

Accepted Answer

It is the natural pacemaker of the heart

Answer

It controls AV conduction

Answer

It initiates the QRS complex

Answer

It plays no significant role

Question 9

Which ion channel is primarily responsible for the rapid depolarization phase (upstroke) of the cardiac action potential?

Accepted Answer

Fast sodium channels

Answer

Sodium-potassium pump

Answer

L-type calcium channels

Answer

Potassium-chloride cotransporter

Question 10

What is the primary function of the sinoatrial (SA) node in the heart?

Accepted Answer

Initiates the electrical impulses that trigger the heartbeat

Answer

Regulates the heart rate and conduction of electrical impulses

Answer

Pumps blood from the heart to the body

Answer

Regulates blood pressure

Question 11

Which ECG waveform corresponds to the depolarization of the ventricles?

Accepted Answer

QRS complex

Answer

P wave

Answer

T wave

Answer

U wave

Question 12

Which of the following events can decrease heart rate?

Accepted Answer

Increased vagal activity

Answer

Increased sympathetic activity

Answer

Decreased blood pressure

Answer

Increased body temperature

Question 13

Define the refractory period of a cardiac cell.

Accepted Answer

The time during which the cell cannot respond to a stimulus

Answer

The time during which the cell is most likely to respond to a stimulus

Answer

The time during which the cell is generating an action potential

Answer

The time during which the cell is repolarizing

Question 14

Which ion is primarily responsible for the plateau phase of the cardiac action potential?

Accepted Answer

Calcium

Answer

Sodium

Answer

Potassium

Answer

Chloride

Question 15

What is the main function of the atrioventricular (AV) node?

Accepted Answer

Delays electrical impulses from the atria to the ventricles

Answer

Generates electrical impulses that trigger the heartbeat

Answer

Regulates the heart rate

Answer

Pumps blood from the heart to the body

Question 16

Explain the mechanism of action by which defibrillation treats arrhythmias.

Accepted Answer

Simultaneously depolarizes all cardiac cells, terminating the arrhythmia

Answer

Simultaneously hyperpolarizes all cardiac cells, terminating the arrhythmia

Answer

Increases the refractory period of cardiac cells

Answer

Decreases the refractory period of cardiac cells

Question 17

Which phase of the cardiac action potential involves rapid depolarization?

Accepted Answer

Phase 0

Answer

Phase 1

Answer

Phase 2

Answer

Phase 3

Question 18

Why is the resting membrane potential of pacemaker cells less negative than that of other cardiac cells?

Accepted Answer

Increased sodium ion permeability

Answer

Increased potassium ion permeability

Answer

Decreased chloride ion permeability

Answer

Cell membrane hyperpolarization

Question 19

Which ECG lead provides the best view of the right precordial region?

Accepted Answer

Lead V1

Answer

Lead I

Answer

Lead II

Answer

Lead aVR

Question 20

What is the typical heart rate range for a healthy adult at rest?

Accepted Answer

60-80 bpm

Answer

40-60 beats per minute (bpm)

Answer

80-100 bpm

Answer

100-120 bpm

Question 21

Which ion channel is responsible for the inward sodium current during Phase 0 of the cardiac action potential?

Accepted Answer

Fast sodium channels

Answer

Slow sodium channels

Answer

Potassium channels

Answer

Calcium channels

Question 22

A patient presents with chest pain, shortness of breath, and an abnormal ECG. The ECG shows ST-segment elevation in multiple leads. What is the most likely diagnosis?

Accepted Answer

Myocardial infarction

Answer

Arrhythmia

Answer

Heart failure

Answer

Pericarditis

Question 23

Which drug is used to block the fast sodium channels in the heart?

Accepted Answer

Lidocaine

Answer

Amiodarone

Answer

Digoxin

Answer

Verapamil

Question 24

What is the difference between atrial flutter and atrial fibrillation?

Accepted Answer

Atrial flutter has a regular rhythm while atrial fibrillation has an irregular rhythm.

Answer

Atrial fibrillation has a regular rhythm while atrial flutter has an irregular rhythm.

Answer

They both have regular rhythms.

Answer

They both have irregular rhythms.

Question 25

What is the function of an implantable cardioverter-defibrillator (ICD)?

Accepted Answer

To defibrillate the heart

Answer

To pace the heart

Answer

To prevent blood clots

Answer

To lower blood pressure

Question 26

Which ion channel is chiefly responsible for the rapid depolarization phase of the cardiac action potential?

Accepted Answer

Voltage-gated sodium channel

Answer

Sodium-potassium pump

Answer

Voltage-gated calcium channel

Answer

Potassium-chloride cotransporter

Question 27

What is the specific ECG waveform that corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Answer

P wave

Answer

T wave

Answer

U wave

Question 28

Which arrhythmia is characterized by a heart rate that is less than 60 beats per minute?

Accepted Answer

Bradycardia

Answer

Tachycardia

Answer

Ventricular fibrillation

Answer

Atrial flutter

Question 29

Which ion plays the dominant role in the repolarization phase of the cardiac action potential?

Accepted Answer

Potassium

Answer

Sodium

Answer

Calcium

Answer

Chloride

Question 30

Which drug classification is frequently used to treat supraventricular arrhythmias?

Accepted Answer

Antiarrhythmics

Answer

Beta-blockers

Answer

Calcium channel blockers

Answer

ACE inhibitors

Question 31

Define the refractory period of a cardiac cell.

Accepted Answer

The period during which the cell is unable to respond to a second stimulus

Answer

The period during which the cell is fully depolarized

Answer

The period during which the cell is hyperpolarized

Answer

The period during which the cell is repolarizing

Question 32

What is the primary purpose of implantable cardioverter-defibrillator (ICD) therapy?

Accepted Answer

Preventing sudden cardiac death

Answer

Controlling heart rate

Answer

Improving cardiac function

Answer

Diagnosing arrhythmias

Question 33

In the cardiac action potential, which phase represents the repolarization of the cell membrane, bringing it back to its resting state?

Accepted Answer

Phase 3

Answer

Phase 0

Answer

Phase 1

Answer

Phase 2

Question 34

Which ion primarily contributes to the rapid depolarization of the cardiac cell during the initial phase of the action potential?

Accepted Answer

Sodium

Answer

Potassium

Answer

Calcium

Answer

Chloride

Question 35

In an electrocardiogram (ECG), which wave corresponds to the electrical depolarization of the atria?

Accepted Answer

P wave

Answer

QRS complex

Answer

T wave

Answer

U wave

Question 36

Which condition is characterized by rapid and chaotic electrical activity originating in the atria?

Accepted Answer

Atrial fibrillation

Answer

Atrial flutter

Answer

Ventricular tachycardia

Answer

Ventricular fibrillation

Question 37

Which medication is primarily used to treat atrial fibrillation by suppressing abnormal electrical impulses?

Accepted Answer

Amiodarone

Answer

Digoxin

Answer

Propranolol

Answer

Aspirin

Question 38

Identify the specialized cardiac tissue responsible for initiating the electrical impulse that triggers the heartbeat.

Accepted Answer

Sinoatrial node

Answer

Atrioventricular node

Answer

Bundle of His

Answer

Purkinje fibers

Question 39

Which ion is primarily responsible for maintaining the resting electrical potential across the cardiac cell membrane?

Accepted Answer

Potassium

Answer

Sodium

Answer

Calcium

Answer

Chloride

Question 40

Which term describes the period when cardiac cells are incapable of generating a new action potential due to their recent excitation?

Accepted Answer

Absolute refractory period

Answer

Relative refractory period

Answer

Effective refractory period

Answer

Supernormal refractory period

Question 41

In an ECG, which interval represents the duration from the beginning of the QRS complex to the end of the T wave?

Accepted Answer

QT interval

Answer

PR interval

Answer

RR interval

Answer

ST segment

Question 42

What is the name of the graphical representation of the electrical activity of the heart, commonly used to diagnose cardiac conditions?

Accepted Answer

Electrocardiogram (ECG)

Answer

Electroencephalogram (EEG)

Answer

Electromyogram (EMG)

Answer

Echocardiogram

Question 43

Which ion channel is primarily responsible for the rapid depolarization phase of the cardiac action potential?

Accepted Answer

Fast sodium channels

Answer

Sodium-potassium pump

Answer

Slow calcium channels

Answer

Potassium channels

Question 44

On an electrocardiogram (ECG), which wave corresponds to ventricular repolarization?

Accepted Answer

T wave

Answer

P wave

Answer

QRS complex

Answer

U wave

Question 45

A defining characteristic of atrial flutter is:

Accepted Answer

Regular atrial rate of 250-350 beats per minute (bpm)

Answer

Irregular atrial rate of 350-450 bpm

Answer

Regular ventricular rate of 150-250 bpm

Answer

Presence of QRS complexes

Question 46

The primary mechanism of action of digoxin, an antiarrhythmic drug, is:

Accepted Answer

Prolongation of the cardiac refractory period

Answer

Inhibition of vagal nerve activity

Answer

Blockade of sodium channels in the heart

Answer

Enhancement of calcium influx into cardiac cells

Question 47

The specialized tissue that initiates the electrical impulse in the heart is called the:

Accepted Answer

Sinoatrial node

Answer

Atrioventricular node

Answer

Bundle of His

Answer

Purkinje fibers

Question 48

Which type of ionic current contributes to the plateau phase of the cardiac action potential?

Accepted Answer

L-type calcium current

Answer

Inward rectifier potassium current

Answer

Transient outward potassium current

Answer

Sodium-calcium exchanger current

Question 49

The primary function of the pacemaker potential in the sinoatrial node is to:

Accepted Answer

Ensure a regular and spontaneous initiation of electrical impulses

Answer

Regulate the rate of impulse conduction through the heart

Answer

Prevent the development of arrhythmias

Answer

Enhance the contractility of the heart muscle

Question 50

Which of the following is the primary contributor to the resting membrane potential of cardiac cells?

Accepted Answer

Potassium permeability

Answer

Calcium permeability

Answer

Chloride permeability

Answer

Sodium permeability

Question 51

The rapid influx of sodium ions during which phase of the cardiac action potential leads to depolarization?

Accepted Answer

Phase 0

Answer

Phase 2

Answer

Phase 1

Answer

Phase 3

Question 52

Which component of the ECG corresponds to the depolarization of the ventricles?

Accepted Answer

QRS complex

Answer

T wave

Answer

P wave

Answer

U wave

Question 53

Atrial fibrillation is a type of arrhythmia characterized by:

Accepted Answer

Rapid and disorganized contractions of the atria

Answer

Slow and regular contractions of the ventricles

Answer

Alternating contractions of the atria and ventricles

Answer

Complete absence of cardiac contractions

Question 54

The refractory period of cardiac muscle refers to the:

Accepted Answer

Interval during which the cells are resistant to further excitation

Answer

Duration of the cardiac action potential

Answer

Period of electrical quiescence following depolarization

Answer

Time required for repolarization to complete

Question 55

Which of the following is a major risk factor for sudden cardiac death?

Accepted Answer

Ventricular fibrillation

Answer

Atrial flutter

Answer

Supraventricular tachycardia

Answer

Bradycardia

Question 56

The specialized cardiac tissue responsible for conducting electrical impulses from the atria to the ventricles is the:

Accepted Answer

Atrioventricular node

Answer

Sinoatrial node

Answer

Bundle of His

Answer

Purkinje fibers

Question 57

Prolonged QT interval on an electrocardiogram may increase the risk of:

Accepted Answer

Torsades de pointes

Answer

Bradycardia

Answer

Increased blood pressure

Answer

Increased contractility