Cardiac Action Potential Overview
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Questions and Answers

What is primarily responsible for making the interior of a resting cardiac cell electrically negative?

  • Low concentrations of Ca2+ ions
  • Low concentrations of K+ ions
  • High concentrations of Na+ ions
  • High concentrations of K+ ions (correct)

    • During which phase of the action potential does rapid influx of Na+ occur?

  • Phase 0 (correct)
  • Phase 4
  • Phase 1
  • Phase 2

    • What occurs during Phase 2 of the cardiac action potential?

  • Complete depolarization of the cell
  • Rapid repolarization due to K+ outflow
  • Sustained plateau due to Ca2+ influx (correct)
  • Restoration of K+ concentrations

    • What characterizes WPW syndrome?

    <p>Atrio-ventricular re-entrant tachycardia</p> Signup and view all the answers

    Which of the following describes first-degree AV conduction block?

    <p>Consistently prolonged PR intervals</p> Signup and view all the answers

    What mechanism restores Na+ and K+ ion concentrations in the heart cell after an action potential?

    <p>Na+/K+ pump</p> Signup and view all the answers

    What is the primary outcome during Phase 3 of the cardiac action potential?

    <p>Rapid repolarization due to K+ outflow</p> Signup and view all the answers

    What effect do Class IA antiarrhythmic drugs have on action potential duration (APD)?

    <p>Increase both APD and ERP</p> Signup and view all the answers

    Which event characterizes Phase 1 of the cardiac action potential?

    <p>Tempory outward flow of K+ ions</p> Signup and view all the answers

    What is a primary effect of Class IB antiarrhythmic drugs on conduction properties?

    <p>Decrease APD and weakly block Na+ channels</p> Signup and view all the answers

    Which of the following statements about antiarrhythmic drugs is accurate?

    <p>Many alter automaticity, conduction velocity, refractory period, and membrane responsiveness</p> Signup and view all the answers

    What happens during Phase 4 of the cardiac action potential?

    <p>The resting state is restored</p> Signup and view all the answers

    Which of the following ions are mainly extracellular in the resting state of the cardiac action potential?

    <p>Na+ and Ca2+</p> Signup and view all the answers

    Which of the following best represents a characteristic of Class II antiarrhythmic drugs?

    <p>They selectively target beta-adrenergic receptors</p> Signup and view all the answers

    In the Vaughan Williams classification system, which class would Quinidine fall under?

    <p>Class IA</p> Signup and view all the answers

    What mechanism characterizes the action of most antiarrhythmic drugs?

    <p>They alter heart rate through changes in automaticity</p> Signup and view all the answers

    What is primarily indicated by an increase in the slope of phase 4 in cardiac action potentials?

    <p>Shortening of intervals between cardiac cycles</p> Signup and view all the answers

    Which structure serves as the dominant pacemaker under normal physiological conditions?

    <p>SA node</p> Signup and view all the answers

    What term is used to describe the spontaneous repetitive firing of myocardial cells under certain pathological conditions?

    <p>Abnormal automaticity</p> Signup and view all the answers

    Which of the following components conducts electrical impulses from the SA node to the ventricles?

    <p>Bundle branches</p> Signup and view all the answers

    In an ECG, what does the P wave represent?

    <p>Atrial contraction</p> Signup and view all the answers

    Normal myocardial cells are characterized by which of the following?

    <p>Inability to generate electrical impulses</p> Signup and view all the answers

    What type of cells compete with the SA node for control of the heart under pathological conditions?

    <p>Ectopic pacemakers</p> Signup and view all the answers

    What physiological change occurs during tachycardia?

    <p>Shortened intervals between cardiac cycles</p> Signup and view all the answers

    What does the QRS complex represent?

    <p>Ventricular depolarization and contraction</p> Signup and view all the answers

    Which of the following is NOT a cause of cardiac arrhythmia?

    <p>Previous heart surgery</p> Signup and view all the answers

    Ectopic beats can be caused by which of the following abnormalities?

    <p>Abnormal impulse formation</p> Signup and view all the answers

    What characterizes re-entry in cardiac impulses?

    <p>Circus movement around a conducting area</p> Signup and view all the answers

    Atrial flutter and fibrillation are commonly caused by which phenomenon?

    <p>Re-entry of impulses</p> Signup and view all the answers

    Which of the following is specifically an example of re-entry?

    <p>Wolff–Parkinson–White syndrome</p> Signup and view all the answers

    Ventricular repolarization is represented by which part of the ECG?

    <p>ST segment and T wave</p> Signup and view all the answers

    Which arrhythmia is characterized by a slow heart rate?

    <p>Sinus bradycardia</p> Signup and view all the answers

    Which class of drugs primarily blocks Na+ channels and does not affect ERP?

    <p>Class I</p> Signup and view all the answers

    What effect do beta-blockers have on AV conduction?

    <p>They decrease AV conduction</p> Signup and view all the answers

    Which drug is classified as a potassium channel blocker?

    <p>Amiodarone</p> Signup and view all the answers

    What is the primary action of Class IV drugs in cardiac treatment?

    <p>They inhibit Ca2+ channels</p> Signup and view all the answers

    Which of the following drugs is NOT classified under beta-blockers?

    <p>Dronedarone</p> Signup and view all the answers

    What effect do Class III K+ channel blockers primarily have on ERP?

    <p>They increase ERP</p> Signup and view all the answers

    Which of the following is an unclassified cardiac drug?

    <p>Adenosine</p> Signup and view all the answers

    Which class of drugs has a significant effect on AV conduction via direct inhibition?

    <p>Class II</p> Signup and view all the answers

    AV conduction can be completely blocked in third-degree heart block.

    <p>True</p> Signup and view all the answers

    Class IB antiarrhythmic drugs, such as lidocaine, primarily increase the effective refractory period (ERP).

    <p>False</p> Signup and view all the answers

    Automaticity is one of the factors that antiarrhythmic drugs affect.

    <p>True</p> Signup and view all the answers

    The Vaughan Williams classification system assumes that each antiarrhythmic drug has multiple main mechanisms of action.

    <p>False</p> Signup and view all the answers

    First-degree AV block is characterized by a delayed conduction without complete block.

    <p>True</p> Signup and view all the answers

    Class IA antiarrhythmic drugs are known for their ability to strongly reduce sodium channel activity.

    <p>False</p> Signup and view all the answers

    Class II antiarrhythmic drugs specifically act as Na+ channel blockers.

    <p>False</p> Signup and view all the answers

    Ventricular tachycardia can be associated with an accessory AV pathway.

    <p>True</p> Signup and view all the answers

    The QRS complex represents the spread of depolarization wave through the atria.

    <p>False</p> Signup and view all the answers

    Abnormal impulse generation can lead to arrhythmias, such as sinus tachycardia.

    <p>True</p> Signup and view all the answers

    Re-entry is a phenomenon that causes impulses to circulate around an area in a bidirectional manner.

    <p>False</p> Signup and view all the answers

    Wolff–Parkinson–White syndrome is a type of defined re-entry condition.

    <p>True</p> Signup and view all the answers

    Atrial flutter and fibrillation are primarily caused by abnormal impulse conduction.

    <p>False</p> Signup and view all the answers

    Sinus bradycardia is an example of extranodal abnormal impulse generation.

    <p>False</p> Signup and view all the answers

    The ST segment in an ECG represents atrial contraction.

    <p>False</p> Signup and view all the answers

    The slope of phase 4 indicates when the first action potential begins.

    <p>False</p> Signup and view all the answers

    Ectopic beats can result from both abnormal impulse generation and conduction.

    <p>True</p> Signup and view all the answers

    Cardiac automaticity allows normal myocardial cells to generate electrical impulses.

    <p>False</p> Signup and view all the answers

    Ectopic pacemakers gain control over the heart by having lower automaticity than the SA node.

    <p>False</p> Signup and view all the answers

    The P wave in an ECG represents ventricular contraction.

    <p>False</p> Signup and view all the answers

    The bundle of His is responsible for the rapid propagation of electrical impulses to the SA node.

    <p>False</p> Signup and view all the answers

    Under normal conditions, the SA node exhibits the lowest automaticity in the heart.

    <p>False</p> Signup and view all the answers

    The electrical activity in the heart transitions from the AV node to the atria.

    <p>False</p> Signup and view all the answers

    Increased slope of phase 4 in the cardiac action potential is associated with bradycardia.

    <p>False</p> Signup and view all the answers

    In the resting state of a cardiac cell, K+ ions are primarily extracellular.

    <p>False</p> Signup and view all the answers

    Phase 2 of the action potential is characterized by a rapid outflow of K+ ions.

    <p>False</p> Signup and view all the answers

    The Na+/K+ pump restores Na+ ions inside the cell during Phase 4 of the cardiac action potential.

    <p>False</p> Signup and view all the answers

    Phase 1 of the action potential involves a short period of rapid depolarization due to Na+ influx.

    <p>False</p> Signup and view all the answers

    The interior of a resting cardiac cell is electrically positive due to the presence of Na+ and Ca2+ ions.

    <p>False</p> Signup and view all the answers

    During Phase 3 of the action potential, there is a rapid influx of Ca2+ ions.

    <p>False</p> Signup and view all the answers

    Rapid redistribution of ions across the cell membrane occurs during four phases of action potential.

    <p>True</p> Signup and view all the answers

    Phase 4 is the phase where the cell is prepared for the next action potential.

    <p>True</p> Signup and view all the answers

    Class I antiarrhythmic drugs primarily block K+ channels and have no effect on ERP.

    <p>False</p> Signup and view all the answers

    Class III antiarrhythmic drugs primarily increase the effective refractory period (ERP).

    <p>True</p> Signup and view all the answers

    Calcium channel blockers mainly inhibit Na+ channels and decrease ERP.

    <p>False</p> Signup and view all the answers

    Beta-blockers exert their effects by decreasing AV conduction and inhibiting phase 4 depolarization.

    <p>True</p> Signup and view all the answers

    The unclassified drug digoxin predominantly blocks Na+ channels in cardiac cells.

    <p>False</p> Signup and view all the answers

    Dronedarone is an example of a Class II antiarrhythmic drug.

    <p>False</p> Signup and view all the answers

    Amiodarone is a drug that inhibits mainly K+ channels and increases ERP.

    <p>True</p> Signup and view all the answers

    Phase 4 depolarization is significantly inhibited by Class I antiarrhythmic drugs.

    <p>False</p> Signup and view all the answers

    What does the ST segment and T wave in an ECG represent?

    <p>They represent ventricular repolarization.</p> Signup and view all the answers

    What is re-entry in the context of cardiac arrhythmias?

    <p>Re-entry is a circular movement of an impulse that excites the conducting system multiple times.</p> Signup and view all the answers

    Identify one example of abnormal impulse generation related to arrhythmias.

    <p>Sinus tachycardia is an example of abnormal impulse generation.</p> Signup and view all the answers

    Describe the primary distinction between normal impulse generation and extranodal abnormality.

    <p>Normal impulse generation originates from the SA node, while extranodal abnormality involves ectopic beats outside the primary pacemaker.</p> Signup and view all the answers

    What common arrhythmia results from a re-entry circuit?

    <p>Atrial flutter is a common arrhythmia resulting from re-entry circuits.</p> Signup and view all the answers

    What can be classified as a disturbance in the normal heart rhythm?

    <p>Cardiac arrhythmia is classified as a disturbance in the normal heart rhythm.</p> Signup and view all the answers

    Give one example of an abnormal impulse conduction issue.

    <p>Wolff-Parkinson-White syndrome is an example of abnormal impulse conduction.</p> Signup and view all the answers

    What does the QRS complex represent in an ECG?

    <p>The QRS complex represents the spread of depolarization through the ventricles.</p> Signup and view all the answers

    What is the relationship between the slope of phase 4 and heart rate variability?

    <p>An increased slope of phase 4 shortens the distance between cardiac cycles, resulting in tachycardia.</p> Signup and view all the answers

    Which cells in the heart primarily exhibit automaticity under normal conditions?

    <p>The SA node cells exhibit automaticity and serve as the dominant pacemaker.</p> Signup and view all the answers

    What occurs when myocardial cells gain abnormal automaticity?

    <p>Myocardial cells may develop spontaneous repetitive firing, known as ectopy, and compete with the SA node.</p> Signup and view all the answers

    How does electrical activity propagate from the SA node to the ventricles?

    <p>Electrical impulses spread from the SA node to the ventricles via the AV node and the bundle of His.</p> Signup and view all the answers

    What does the P wave represent in an ECG?

    <p>The P wave represents the spread of depolarization through the atria, indicating atrial contraction.</p> Signup and view all the answers

    What characteristic distinguishes normal myocardial cells from those that exhibit automaticity?

    <p>Normal myocardial cells do not possess automaticity and cannot generate electrical impulses.</p> Signup and view all the answers

    What impact does a pathological condition have on myocardial cells regarding automaticity?

    <p>Pathological conditions may cause some myocardial cells to acquire abnormal automaticity, leading to ectopic pacemakers.</p> Signup and view all the answers

    In the context of cardiac cycles, what does tachycardia indicate about the slope of phase 4?

    <p>Tachycardia indicates that the slope of phase 4 is increased, leading to shorter intervals between cardiac cycles.</p> Signup and view all the answers

    What is the primary effect of Class IC antiarrhythmic drugs on ion channels?

    <p>They strongly block Na+ channels with no effect on ERP.</p> Signup and view all the answers

    How do beta-blockers, as classified in Class II, alter AV conduction?

    <p>They decrease AV conduction and inhibit phase 4 depolarization.</p> Signup and view all the answers

    What is the primary action of Class III antiarrhythmic drugs like amiodarone?

    <p>They primarily block K+ channels and increase ERP.</p> Signup and view all the answers

    What ion channels are predominantly affected by Class IV antiarrhythmic drugs?

    <p>They mainly inhibit Ca2+ channels and increase ERP.</p> Signup and view all the answers

    What distinguishes unclassified drugs like digoxin from the traditional antiarrhythmic classes?

    <p>They do not fit neatly into the Vaughan Williams classification and have unique mechanisms.</p> Signup and view all the answers

    Explain how Class III K+ channel blockers affect the effective refractory period (ERP).

    <p>They increase ERP by prolonging the repolarization phase.</p> Signup and view all the answers

    What is a notable physiological outcome of using sodium channel blockers in Class I antiarrhythmic drugs?

    <p>They can reduce the conduction velocity of electrical impulses in the heart.</p> Signup and view all the answers

    Identify one major effect of potassium channel blockers on cardiac action potential duration.

    <p>They prolong the action potential duration (APD).</p> Signup and view all the answers

    What role do accessory AV pathways play in WPW syndrome?

    <p>They create a reentrant circuit that facilitates rapid heart rates.</p> Signup and view all the answers

    Describe the primary impact of Class IA antiarrhythmic drugs on cardiac action potentials.

    <p>They moderately block Na+ channels, increasing both the effective refractory period (ERP) and action potential duration (APD).</p> Signup and view all the answers

    What defines the mechanism of action for Class IB antiarrhythmic drugs?

    <p>They weakly block Na+ channels, resulting in decreased ERP and shortened action potential duration (APD).</p> Signup and view all the answers

    What does third-degree AV block indicate about conduction in the heart?

    <p>It indicates a complete block of electrical conduction through the AV node, leading to dissociation between atrial and ventricular activity.</p> Signup and view all the answers

    How do antiarrhythmic drugs affect membrane responsiveness in cardiac cells?

    <p>They alter membrane excitability, which can stabilize abnormal cardiac rhythms.</p> Signup and view all the answers

    What is the significance of refractory periods in the action of antiarrhythmic agents?

    <p>Refractory periods determine the timing of subsequent action potentials, influencing the heart's rhythm stability.</p> Signup and view all the answers

    What characterizes Class II antiarrhythmic drugs and their action on the heart?

    <p>They primarily act as beta-blockers, reducing heart rate and AV conduction.</p> Signup and view all the answers

    Explain the importance of understanding action potential duration (APD) in cardiology.

    <p>APD influences the timing of cardiac contractions, critical for effective heart function and arrhythmia management.</p> Signup and view all the answers

    During which phase of the cardiac action potential does a plateau occur and why?

    <p>Phase 2, due to the slow influx of Ca++ ions.</p> Signup and view all the answers

    What role do K+ ions play during Phase 1 of the cardiac action potential?

    <p>K+ ions rapidly exit the cell, contributing to repolarization.</p> Signup and view all the answers

    How do Na+/K+ pumps contribute to Phase 4 of the cardiac action potential?

    <p>They restore the ionic concentrations, extruding Na+ and bringing K+ back into the cell.</p> Signup and view all the answers

    Which ion movements characterize the transition from the resting state to Phase 0 in cardiac action potential?

    <p>A rapid influx of Na+ ions into the cell initiates depolarization.</p> Signup and view all the answers

    What is the significance of Ca++ ion influx during the cardiac action potential?

    <p>It prolongs the action potential during Phase 2, aiding in muscle contraction.</p> Signup and view all the answers

    Explain the basic electrical situation of a resting cardiac cell.

    <p>In a resting cardiac cell, K+ ions are primarily intracellular while Na+ and Ca2+ ions are mainly extracellular.</p> Signup and view all the answers

    What characterizes Phase 3 of the cardiac action potential?

    <p>Rapid repolarization occurs due to the outflow of K+ ions.</p> Signup and view all the answers

    Describe the phases of action potential and their role in cardiac function.

    <p>The phases include depolarization, early repolarization, plateau, and final repolarization, which collectively govern contraction and relaxation.</p> Signup and view all the answers

    In the resting state, K+ ions are found mainly ______, while Na+ and Ca2+ are mainly extracellular.

    <p>intracellular</p> Signup and view all the answers

    During Phase 0 of the cardiac action potential, there is a rapid influx of ______.

    <p>Na+</p> Signup and view all the answers

    Phase 2 of the action potential is characterized by a 'plateau' due to slow influx of ______.

    <p>Ca2+</p> Signup and view all the answers

    Phase 3 of the cardiac action potential involves rapid outflow of ______.

    <p>K+</p> Signup and view all the answers

    Phase 4 of the action potential refers to the ______ state being restored.

    <p>resting</p> Signup and view all the answers

    The Na+/K+ pump is responsible for extruding Na+ ions out of the cell and returning ______ ions back.

    <p>K+</p> Signup and view all the answers

    A characteristic of antiarrhythmic drugs is that they can affect ______ in cardiac action potentials.

    <p>automaticity</p> Signup and view all the answers

    Class IA antiarrhythmic drugs are known for their ability to strongly reduce ______ channel activity.

    <p>sodium</p> Signup and view all the answers

    The QRS complex represents the spread of depolarization wave through the ______.

    <p>ventricles</p> Signup and view all the answers

    The ST segment and T wave represent ventricular ______.

    <p>repolarization</p> Signup and view all the answers

    Arrhythmia means disturbance in the normal heart ______.

    <p>rhythm</p> Signup and view all the answers

    Abnormal impulse generation can lead to arrhythmias, such as sinus ______.

    <p>tachycardia</p> Signup and view all the answers

    Re-entry is a circus movement of an impulse that circulates around a certain area in a ______ direction.

    <p>unidirectional</p> Signup and view all the answers

    Wolff–Parkinson–White syndrome is an example of a defined ______.

    <p>re-entry</p> Signup and view all the answers

    Ectopic beats can be caused by either abnormal impulse generation or ______.

    <p>conduction</p> Signup and view all the answers

    Atrial flutter and fibrillation are commonly caused by ______ re-entry.

    <p>atrial</p> Signup and view all the answers

    The slope of phase 4 determines when the 2nd action potential starts. When the slope is increased, the distance between 2 cardiac cycles shortens (i.e. ______).

    <p>tachycardia</p> Signup and view all the answers

    Cardiac automaticity refers to the ability of certain cells to self-generate electrical impulses that spread throughout the ______.

    <p>heart</p> Signup and view all the answers

    Under normal conditions, the SA node is the dominant ______ (i.e. has the highest automaticity).

    <p>pacemaker</p> Signup and view all the answers

    In the ECG, the P wave represents the spread of depolarization wave through the ______ (atrial contraction).

    <p>atria</p> Signup and view all the answers

    Normal myocardial cells don’t have automaticity i.e. cannot generate ______.

    <p>impulses</p> Signup and view all the answers

    Ectopic pacemakers compete with the SA node for control of the ______.

    <p>heart</p> Signup and view all the answers

    Impulse conduction spreads from the SA node to the ventricles via the AV node and the bundle of ______.

    <p>His</p> Signup and view all the answers

    Under certain pathological conditions, some myocardial cells may acquire spontaneous repetitive firing, this is called abnormal automaticity or ______.

    <p>ectopy</p> Signup and view all the answers

    Class IC drugs, such as ______, strongly block Na+ channels.

    <p>flecainide</p> Signup and view all the answers

    Beta-blockers, like ______, inhibit phase 4 depolarization.

    <p>propranolol</p> Signup and view all the answers

    Class III K+ channel blockers include drugs like ______ and dronedarone.

    <p>amiodarone</p> Signup and view all the answers

    Class IV drugs primarily inhibit ______ channels and increase ERP.

    <p>Ca2+</p> Signup and view all the answers

    An example of an unclassified drug is ______.

    <p>digoxin</p> Signup and view all the answers

    Class III drugs primarily affect ______ channel activity and ERP.

    <p>K+</p> Signup and view all the answers

    The drug ______ is known to block both sodium and potassium channels.

    <p>sotalol</p> Signup and view all the answers

    Calcium channel blockers like ______ are used to affect AV conduction.

    <p>diltiazem</p> Signup and view all the answers

    WPW syndrome is a type of atrioventricular re-entry tachycardia caused by an accessory AV ______ pathway.

    <p>conducting</p> Signup and view all the answers

    Antiarrhythmic drugs can alter factors such as automaticity, conduction velocity, refractory period, and membrane ______.

    <p>responsiveness</p> Signup and view all the answers

    Class IA antiarrhythmic drugs, such as quinidine and procainamide, moderately block Na+ channels and increase ______.

    <p>ERP</p> Signup and view all the answers

    Class IB antiarrhythmic drugs, like lidocaine, weakly block Na+ channels and decrease ______.

    <p>ERP</p> Signup and view all the answers

    Heart block can be classified as first-degree, second-degree, or third-degree, with third-degree being ______ blocked.

    <p>completely</p> Signup and view all the answers

    The Vaughan Williams classification assumes that each antiarrhythmic drug has one main mechanism of ______.

    <p>action</p> Signup and view all the answers

    Most antiarrhythmic drugs have more than one ______ of action.

    <p>mechanism</p> Signup and view all the answers

    Class II antiarrhythmic drugs primarily act on ______ channels.

    <p>Na+</p> Signup and view all the answers

    Match the following classes of antiarrhythmic drugs with their primary action:

    <p>Class I = Inhibit Na+ channels without affecting ERP Class II = Beta-blockers that decrease AV conduction Class III = Primarily block K+ channels and increase ERP Class IV = Inhibit Ca2+ channels and increase ERP</p> Signup and view all the answers

    Match the following antiarrhythmic drugs with their class:

    <p>Flecainide = Class I Amiodarone = Class III Diltiazem = Class IV Propranolol = Class II</p> Signup and view all the answers

    Match the following drugs with their unique characteristic:

    <p>Digoxin = Unclassified drug with cardiac glycoside properties Adenosine = Rapid antiarrhythmic effect in paroxysmal SVT Magnesium sulfate = Used in torsades de pointes Dronedarone = K+ channel blocker with multiple actions</p> Signup and view all the answers

    Match the following terms with their corresponding definitions:

    <p>ERP = Effective refractory period Phase 4 = Diastolic depolarization AV conduction = Impulse transmission through the atrioventricular node Ectopic beats = Abnormal impulses originating outside the SA node</p> Signup and view all the answers

    Match the following actions with the drug class responsible:

    <p>Decrease AV conduction = Beta-blockers (Class II) Prolong the refractory period = K+ channel blockers (Class III) Inhibit Na+ channels = Class I antiarrhythmics Inhibit Ca2+ channels = Class IV antiarrhythmics</p> Signup and view all the answers

    Match the following drug effects with their corresponding classes:

    <p>Flecainide = No effect on ERP Amiodarone = Increases ERP significantly Diltiazem = Increases ERP by inhibiting Ca2+ Propranolol = Decreases heart rate and AV conduction</p> Signup and view all the answers

    Match the following antiarrhythmic drugs with their specific function:

    <p>Sotalol = K+ channel blocker with influence on ERP Lidocaine = Class IB agent for ventricular arrhythmias Verapamil = Ca2+ channel blocker affecting nodal tissues Bipyridines = Inhibit phosphodiesterase and increase calcium availability</p> Signup and view all the answers

    Match the following cardiac conditions with the appropriate drug class treatment:

    <p>Atrial fibrillation = Beta-blockers or Ca2+ channel blockers Supraventricular tachycardia = Adenosine Ventricular tachycardia = Class I or III antiarrhythmics Torsades de pointes = Magnesium sulfate</p> Signup and view all the answers

    Match the following cardiac terms with their definitions:

    <p>Automaticity = The ability of certain cardiac cells to self-generate electrical impulses Ectopic pacemakers = Cardiac cells that compete with the SA node for control under pathological conditions Tachycardia = Shortening of the distance between two cardiac cycles due to increased slope AV Node = The node that transmits electrical activity from the SA node to the ventricles</p> Signup and view all the answers

    Match the following ECG waveforms with their meanings:

    <p>P wave = Represents the spread of depolarization through the atria QRS complex = Represents the depolarization of the ventricles T wave = Indicates ventricular repolarization U wave = May represent afterdepolarizations or electrolyte imbalances</p> Signup and view all the answers

    Match the following cardiac arrhythmia mechanisms with their descriptions:

    <p>Abnormal impulse generation = Results from conditions like sinus tachycardia Abnormal impulse conduction = Refers to disturbances in the normal rhythm Re-entry = A circular movement of impulse that excites the conduction system multiple times Extranodal abnormalities = Includes ectopic beats such as premature atrial contractions</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Ventriular depolarization = Represents the QRS complex on an ECG Ventricular repolarization = Is indicated by the ST segment and T wave Sinus bradycardia = Characterized by a slow heart rate originating from the SA node Atrial flutter = Commonly caused by re-entry in the atria</p> Signup and view all the answers

    Match the following cardiac phases with their characteristics:

    <p>Phase 4 = Associated with the resting membrane potential and slope increase Phase 2 = Involves calcium influx and prolonged depolarization Phase 3 = Characterized by rapid repolarization due to potassium efflux Phase 1 = Involves initial repolarization and sodium channel closure</p> Signup and view all the answers

    Match the following types of arrhythmias with their descriptions:

    <p>Sinus tachycardia = Increased heart rate greater than 100 beats per minute Atrial fibrillation = Irregular and rapid heart rate due to chaotic atrial electrical activity Premature ventricular contractions = Ectopic beats originating from the ventricles Ventricular tachycardia = Rapid heart rate that originates in the ventricles</p> Signup and view all the answers

    Match the following arrhythmias with their causes:

    <p>Atrial fibrillation = Often results from circuses of re-entry impulses Wolff–Parkinson–White syndrome = An example of defined re-entry in cardiac conduction Premature ventricular contractions = Caused by ectopic impulses in the ventricles Sinus tachycardia = A result of abnormal impulse generation</p> Signup and view all the answers

    Match the following cardiac conduction components with their functions:

    <p>SA Node = Acts as the primary pacemaker of the heart Bundle of His = Conducts impulses from the AV node to the ventricular branches Right and Left Bundle Branches = Distribute impulses to the ventricles Purkinje fibers = Facilitate rapid conduction to the ventricular myocardium</p> Signup and view all the answers

    Match the following ECG waveforms with their representative actions:

    <p>P wave = Indicates atrial depolarization QRS complex = Represents ventricular contraction ST segment = Signifies the period of ventricular repolarization T wave = Reflects the process of ventricular relaxation</p> Signup and view all the answers

    Match the following concepts in cardiac physiology with their relevant examples:

    <p>Ectopic beats = Premature atrial contractions and premature ventricular contractions Normal impulse formation = Sinus tachycardia as an example of impulse disturbance Reentry mechanisms = Circulation of impulses around a unidirectional block Abnormal conduction = Illustrated by conditions like third-degree AV block</p> Signup and view all the answers

    Match the following conditions with their effects on the heart:

    <p>Increased slope of phase 4 = Leads to decrease in the duration between cardiac cycles Automaticity loss in myocardial cells = Results in inability to generate impulses Ectopia = Leads to abnormal impulse generation competing with the SA node SA Node dominance = Maintains normal pacemaking activity under usual circumstances</p> Signup and view all the answers

    Match the following terms to their related cardiac events:

    <p>Ventricular contraction = Depicted by the QRS complex Ventricular relaxation = Illustrated by the ST segment and T wave Normal heart rhythm disturbance = Described as cardiac arrhythmia Impulse re-entry = Can lead to atrial flutter and fibrillation</p> Signup and view all the answers

    Match the following types of myocardial cells with their characteristics:

    <p>Normal myocardial cells = Do not possess automaticity and cannot generate impulses Pacemaker cells = Have the highest automaticity and can self-generate impulses Pathological myocardial cells = May acquire spontaneous repetitive firing Ectopic pacemaker cells = Compete with the SA node for control of heart rhythm</p> Signup and view all the answers

    Match the following types of arrhythmias with their characteristics:

    <p>Sinus tachycardia = Caused by abnormal impulse generation Atrial flutter = Resulting from re-entry mechanisms Ventricular fibrillation = An emergency condition due to chaotic impulses Third-degree AV block = Represents a complete block of impulse conduction</p> Signup and view all the answers

    Match the following definitions with the correct terms:

    <p>Re-entry = A phenomenon that can lead to arrhythmias due to circular conduction Ectopic beats = Preceding contractions that arise from locations other than the SA node Atrial contraction = Represented by the P wave on an ECG Myocardial depolarization = Initiated by electrical activity spreading through the cardiac conduction system</p> Signup and view all the answers

    Match the following types of cardiac cells or rhythms with their definitions:

    <p>Normal myocardial cells = Typically characterized by stable resting potentials Ectopic pacemakers = Compete with the SA node during arrhythmias Pacemaker cells = Responsible for impulse generation in the heart Reentrant circuits = Associated with rapid and repetitive impulse conduction</p> Signup and view all the answers

    Match the antiarrhythmic drug subclass to its primary mechanism of action:

    <p>Class IA = Moderately blocks Na+ channels and increases ERP Class IB = Weakly blocks Na+ channels and decreases ERP Class II = Na+ channel blockers Class III = Potassium channel blockers</p> Signup and view all the answers

    Match the antiarrhythmic drug to its corresponding example:

    <p>Quinidine = Class IA Lidocaine = Class IB Propranolol = Class II Sotalol = Class III</p> Signup and view all the answers

    Match the classification of heart block to its description:

    <p>First-degree = Delayed conduction without complete block Second-degree = Intermittent conduction block Third-degree = Complete block of conduction Bundle branch block = Impaired conduction in a specific pathway</p> Signup and view all the answers

    Match the effect of Class IA antiarrhythmic drugs to their function:

    <p>Increase ERP = Prolong action potential duration Block Na+ channels = Slow conduction velocity Reduce contractility = Lower heart rate Alter membrane responsiveness = Stabilize cardiac myocytes</p> Signup and view all the answers

    Match the antiarrhythmic drug class to its specific clinical effect:

    <p>Class I = Modulates sodium ion movement Class II = Decreases heart rate Class III = Prolongs repolarization Class IV = Inhibits calcium channels</p> Signup and view all the answers

    Match the cardiac condition to its associated treatment:

    <p>Atrial Fibrillation = Class III drugs Ventricular Tachycardia = Class I drugs Heart Block = Class II drugs Supraventricular Tachycardia = Beta-blockers</p> Signup and view all the answers

    Match the mechanism of action to its effect on cardiac action potentials:

    <p>Automaticity = Spontaneous depolarization Refractory period = Time during which cells cannot depolarize Conduction velocity = Speed of electrical impulse transmission Membrane responsiveness = Sensitivity of myocytes to stimuli</p> Signup and view all the answers

    Match the drug to the class it belongs to based on clinical usage:

    <p>Disopyramide = Class IA Mexiletine = Class IB Atenolol = Class II Dofetilide = Class III</p> Signup and view all the answers

    Match the phases of cardiac action potential with their descriptions:

    <p>Phase 0 = Rapid depolarization due to influx of Na+ Phase 1 = Rapid repolarization due to outflow of K+ Phase 2 = Plateau phase due to slow influx of Ca2+ Phase 3 = Rapid repolarization due to outflow of K+</p> Signup and view all the answers

    Match the antiarrhythmic drug classes with their primary mechanisms:

    <p>Class I = Sodium channel blockers Class II = Beta-adrenergic antagonists Class III = Potassium channel blockers Class IV = Calcium channel blockers</p> Signup and view all the answers

    Match the ion with its location during the resting state of the cardiac cell:

    <p>K+ = Mainly intracellular Na+ = Mainly extracellular Ca2+ = Mainly extracellular Cl- = Mainly intracellular</p> Signup and view all the answers

    Match the concept with its definition in cardiac physiology:

    <p>Re-entry = A mechanism where an impulse circulates through the myocardial tissue Ectopic beats = Abnormal beats originating from outside the SA node Automaticity = The ability of cardiac cells to generate action potentials spontaneously Effective refractory period = Time during which a new action potential cannot be initiated</p> Signup and view all the answers

    Match the effect with the respective class of antiarrhythmic drugs:

    <p>Class IA = Prolongs action potential duration Class IB = Reduces action potential duration Class II = Increases AV conduction time Class IV = Decreases heart rate</p> Signup and view all the answers

    Match the physiological effects to their respective phases of the cardiac action potential:

    <p>Phase 0 = Na+ influx causes rapid depolarization Phase 1 = K+ outflow leads to initial repolarization Phase 2 = Increased Ca2+ leads to plateau Phase 3 = K+ outflow results in repolarization</p> Signup and view all the answers

    Match the terminology with its relevant clinical significance:

    <p>AV block = A condition that affects electrical conduction between atria and ventricles Tachycardia = Increased heart rate above normal Bradycardia = Decreased heart rate below normal Flutter = Rapid and irregular heartbeats</p> Signup and view all the answers

    Match the type of cardiac arrhythmias with their characteristics:

    <p>Atrial flutter = Rapid reentrant tachycardia in atria Ventricular tachycardia = Fast heart rate originating from ventricles Atrial fibrillation = Irregular and often rapid heart rhythm First-degree AV block = Slow conduction through the AV node without missing beats</p> Signup and view all the answers

    Study Notes

    Cardiac Action Potential

    • Resting State: Cell interior is negative; high intracellular K+ and extracellular Na+ and Ca2+.
    • Phases of Action Potential:
      • Phase 0: Rapid depolarization due to Na+ influx.
      • Phase 1: Short rapid repolarization due to K+ outflow.
      • Phase 2: Plateau phase with delayed repolarization; slow Ca2+ influx.
      • Phase 3: Rapid repolarization as K+ exits.
      • Phase 4: Resting state restores; Na+/K+ pump extrudes Na+ and reintroduces K+.

    Impulse Formation and Conduction

    • Automaticity: Cardiac cells can self-generate electrical impulses; SA node is the primary pacemaker.
    • Normal Myocardial Cells: Lack intrinsic automaticity; cannot generate impulses under normal conditions.
    • Ectopic Pacemakers: Abnormal cells may exhibit spontaneous firing, competing with SA node.
    • Impulse Conduction Pathway: Activity spreads from SA node to ventricles via AV node and Bundle of His.

    Electrocardiogram (ECG) Waves

    • P Wave: Represents atrial depolarization and contraction.
    • QRS Complex: Indicates ventricular depolarization and contraction.
    • ST Segment and T Wave: Reflect ventricular repolarization and relaxation.

    Cardiac Arrhythmia

    • Definition: Disturbance of normal heart rhythm due to abnormal impulse generation, conduction, or both.
    • Types of Abnormal Impulse Formation:
      • Nodal Abnormalities: Examples include sinus tachycardia and bradycardia.
      • Extranodal Abnormalities: Includes premature atrial and ventricular contractions.

    Abnormal Impulse Conduction

    • Re-entry Mechanism: Circulating impulses around an area can lead to atrial flutter and fibrillation.
    • Wolff-Parkinson-White Syndrome: A type of defined re-entry caused by an accessory AV pathway leading to tachycardia.

    Heart Block

    • Types:
      • First Degree: Delayed AV conduction.
      • Second Degree: Intermittent blockage.
      • Third Degree: Complete block of impulses from atria to ventricles.

    Antiarrhythmic Drugs

    • Mechanisms of Action: Alter factors like automaticity, conduction velocity, refractory period, and membrane responsiveness.
    • Classifications (based on Vaughan Williams system):
      • Class IA: Moderate Na+ channel blockers (e.g., quinidine).
      • Class IB: Weak Na+ channel blockers, reducing effective refractory period (ERP) (e.g., lidocaine).
      • Class IC: Strong Na+ blockers with no effect on ERP (e.g., flecainide).
      • Class II: Beta-blockers that decrease AV conduction and inhibit phase 4 depolarization (e.g., metoprolol).
      • Class III: K+ channel blockers increasing ERP (e.g., amiodarone).
      • Class IV: Ca2+ channel blockers that increase ERP (e.g., verapamil).
    • Unclassified Drugs: Include digoxin, adenosine, and magnesium sulfate.

    Cardiac Action Potential

    • Resting State: Cell interior is negative; high intracellular K+ and extracellular Na+ and Ca2+.
    • Phases of Action Potential:
      • Phase 0: Rapid depolarization due to Na+ influx.
      • Phase 1: Short rapid repolarization due to K+ outflow.
      • Phase 2: Plateau phase with delayed repolarization; slow Ca2+ influx.
      • Phase 3: Rapid repolarization as K+ exits.
      • Phase 4: Resting state restores; Na+/K+ pump extrudes Na+ and reintroduces K+.

    Impulse Formation and Conduction

    • Automaticity: Cardiac cells can self-generate electrical impulses; SA node is the primary pacemaker.
    • Normal Myocardial Cells: Lack intrinsic automaticity; cannot generate impulses under normal conditions.
    • Ectopic Pacemakers: Abnormal cells may exhibit spontaneous firing, competing with SA node.
    • Impulse Conduction Pathway: Activity spreads from SA node to ventricles via AV node and Bundle of His.

    Electrocardiogram (ECG) Waves

    • P Wave: Represents atrial depolarization and contraction.
    • QRS Complex: Indicates ventricular depolarization and contraction.
    • ST Segment and T Wave: Reflect ventricular repolarization and relaxation.

    Cardiac Arrhythmia

    • Definition: Disturbance of normal heart rhythm due to abnormal impulse generation, conduction, or both.
    • Types of Abnormal Impulse Formation:
      • Nodal Abnormalities: Examples include sinus tachycardia and bradycardia.
      • Extranodal Abnormalities: Includes premature atrial and ventricular contractions.

    Abnormal Impulse Conduction

    • Re-entry Mechanism: Circulating impulses around an area can lead to atrial flutter and fibrillation.
    • Wolff-Parkinson-White Syndrome: A type of defined re-entry caused by an accessory AV pathway leading to tachycardia.

    Heart Block

    • Types:
      • First Degree: Delayed AV conduction.
      • Second Degree: Intermittent blockage.
      • Third Degree: Complete block of impulses from atria to ventricles.

    Antiarrhythmic Drugs

    • Mechanisms of Action: Alter factors like automaticity, conduction velocity, refractory period, and membrane responsiveness.
    • Classifications (based on Vaughan Williams system):
      • Class IA: Moderate Na+ channel blockers (e.g., quinidine).
      • Class IB: Weak Na+ channel blockers, reducing effective refractory period (ERP) (e.g., lidocaine).
      • Class IC: Strong Na+ blockers with no effect on ERP (e.g., flecainide).
      • Class II: Beta-blockers that decrease AV conduction and inhibit phase 4 depolarization (e.g., metoprolol).
      • Class III: K+ channel blockers increasing ERP (e.g., amiodarone).
      • Class IV: Ca2+ channel blockers that increase ERP (e.g., verapamil).
    • Unclassified Drugs: Include digoxin, adenosine, and magnesium sulfate.

    Cardiac Action Potential

    • Resting State: Cell interior is negative; high intracellular K+ and extracellular Na+ and Ca2+.
    • Phases of Action Potential:
      • Phase 0: Rapid depolarization due to Na+ influx.
      • Phase 1: Short rapid repolarization due to K+ outflow.
      • Phase 2: Plateau phase with delayed repolarization; slow Ca2+ influx.
      • Phase 3: Rapid repolarization as K+ exits.
      • Phase 4: Resting state restores; Na+/K+ pump extrudes Na+ and reintroduces K+.

    Impulse Formation and Conduction

    • Automaticity: Cardiac cells can self-generate electrical impulses; SA node is the primary pacemaker.
    • Normal Myocardial Cells: Lack intrinsic automaticity; cannot generate impulses under normal conditions.
    • Ectopic Pacemakers: Abnormal cells may exhibit spontaneous firing, competing with SA node.
    • Impulse Conduction Pathway: Activity spreads from SA node to ventricles via AV node and Bundle of His.

    Electrocardiogram (ECG) Waves

    • P Wave: Represents atrial depolarization and contraction.
    • QRS Complex: Indicates ventricular depolarization and contraction.
    • ST Segment and T Wave: Reflect ventricular repolarization and relaxation.

    Cardiac Arrhythmia

    • Definition: Disturbance of normal heart rhythm due to abnormal impulse generation, conduction, or both.
    • Types of Abnormal Impulse Formation:
      • Nodal Abnormalities: Examples include sinus tachycardia and bradycardia.
      • Extranodal Abnormalities: Includes premature atrial and ventricular contractions.

    Abnormal Impulse Conduction

    • Re-entry Mechanism: Circulating impulses around an area can lead to atrial flutter and fibrillation.
    • Wolff-Parkinson-White Syndrome: A type of defined re-entry caused by an accessory AV pathway leading to tachycardia.

    Heart Block

    • Types:
      • First Degree: Delayed AV conduction.
      • Second Degree: Intermittent blockage.
      • Third Degree: Complete block of impulses from atria to ventricles.

    Antiarrhythmic Drugs

    • Mechanisms of Action: Alter factors like automaticity, conduction velocity, refractory period, and membrane responsiveness.
    • Classifications (based on Vaughan Williams system):
      • Class IA: Moderate Na+ channel blockers (e.g., quinidine).
      • Class IB: Weak Na+ channel blockers, reducing effective refractory period (ERP) (e.g., lidocaine).
      • Class IC: Strong Na+ blockers with no effect on ERP (e.g., flecainide).
      • Class II: Beta-blockers that decrease AV conduction and inhibit phase 4 depolarization (e.g., metoprolol).
      • Class III: K+ channel blockers increasing ERP (e.g., amiodarone).
      • Class IV: Ca2+ channel blockers that increase ERP (e.g., verapamil).
    • Unclassified Drugs: Include digoxin, adenosine, and magnesium sulfate.

    Cardiac Action Potential

    • Resting State: Cell interior is negative; high intracellular K+ and extracellular Na+ and Ca2+.
    • Phases of Action Potential:
      • Phase 0: Rapid depolarization due to Na+ influx.
      • Phase 1: Short rapid repolarization due to K+ outflow.
      • Phase 2: Plateau phase with delayed repolarization; slow Ca2+ influx.
      • Phase 3: Rapid repolarization as K+ exits.
      • Phase 4: Resting state restores; Na+/K+ pump extrudes Na+ and reintroduces K+.

    Impulse Formation and Conduction

    • Automaticity: Cardiac cells can self-generate electrical impulses; SA node is the primary pacemaker.
    • Normal Myocardial Cells: Lack intrinsic automaticity; cannot generate impulses under normal conditions.
    • Ectopic Pacemakers: Abnormal cells may exhibit spontaneous firing, competing with SA node.
    • Impulse Conduction Pathway: Activity spreads from SA node to ventricles via AV node and Bundle of His.

    Electrocardiogram (ECG) Waves

    • P Wave: Represents atrial depolarization and contraction.
    • QRS Complex: Indicates ventricular depolarization and contraction.
    • ST Segment and T Wave: Reflect ventricular repolarization and relaxation.

    Cardiac Arrhythmia

    • Definition: Disturbance of normal heart rhythm due to abnormal impulse generation, conduction, or both.
    • Types of Abnormal Impulse Formation:
      • Nodal Abnormalities: Examples include sinus tachycardia and bradycardia.
      • Extranodal Abnormalities: Includes premature atrial and ventricular contractions.

    Abnormal Impulse Conduction

    • Re-entry Mechanism: Circulating impulses around an area can lead to atrial flutter and fibrillation.
    • Wolff-Parkinson-White Syndrome: A type of defined re-entry caused by an accessory AV pathway leading to tachycardia.

    Heart Block

    • Types:
      • First Degree: Delayed AV conduction.
      • Second Degree: Intermittent blockage.
      • Third Degree: Complete block of impulses from atria to ventricles.

    Antiarrhythmic Drugs

    • Mechanisms of Action: Alter factors like automaticity, conduction velocity, refractory period, and membrane responsiveness.
    • Classifications (based on Vaughan Williams system):
      • Class IA: Moderate Na+ channel blockers (e.g., quinidine).
      • Class IB: Weak Na+ channel blockers, reducing effective refractory period (ERP) (e.g., lidocaine).
      • Class IC: Strong Na+ blockers with no effect on ERP (e.g., flecainide).
      • Class II: Beta-blockers that decrease AV conduction and inhibit phase 4 depolarization (e.g., metoprolol).
      • Class III: K+ channel blockers increasing ERP (e.g., amiodarone).
      • Class IV: Ca2+ channel blockers that increase ERP (e.g., verapamil).
    • Unclassified Drugs: Include digoxin, adenosine, and magnesium sulfate.

    Cardiac Action Potential

    • Resting State: Cell interior is negative; high intracellular K+ and extracellular Na+ and Ca2+.
    • Phases of Action Potential:
      • Phase 0: Rapid depolarization due to Na+ influx.
      • Phase 1: Short rapid repolarization due to K+ outflow.
      • Phase 2: Plateau phase with delayed repolarization; slow Ca2+ influx.
      • Phase 3: Rapid repolarization as K+ exits.
      • Phase 4: Resting state restores; Na+/K+ pump extrudes Na+ and reintroduces K+.

    Impulse Formation and Conduction

    • Automaticity: Cardiac cells can self-generate electrical impulses; SA node is the primary pacemaker.
    • Normal Myocardial Cells: Lack intrinsic automaticity; cannot generate impulses under normal conditions.
    • Ectopic Pacemakers: Abnormal cells may exhibit spontaneous firing, competing with SA node.
    • Impulse Conduction Pathway: Activity spreads from SA node to ventricles via AV node and Bundle of His.

    Electrocardiogram (ECG) Waves

    • P Wave: Represents atrial depolarization and contraction.
    • QRS Complex: Indicates ventricular depolarization and contraction.
    • ST Segment and T Wave: Reflect ventricular repolarization and relaxation.

    Cardiac Arrhythmia

    • Definition: Disturbance of normal heart rhythm due to abnormal impulse generation, conduction, or both.
    • Types of Abnormal Impulse Formation:
      • Nodal Abnormalities: Examples include sinus tachycardia and bradycardia.
      • Extranodal Abnormalities: Includes premature atrial and ventricular contractions.

    Abnormal Impulse Conduction

    • Re-entry Mechanism: Circulating impulses around an area can lead to atrial flutter and fibrillation.
    • Wolff-Parkinson-White Syndrome: A type of defined re-entry caused by an accessory AV pathway leading to tachycardia.

    Heart Block

    • Types:
      • First Degree: Delayed AV conduction.
      • Second Degree: Intermittent blockage.
      • Third Degree: Complete block of impulses from atria to ventricles.

    Antiarrhythmic Drugs

    • Mechanisms of Action: Alter factors like automaticity, conduction velocity, refractory period, and membrane responsiveness.
    • Classifications (based on Vaughan Williams system):
      • Class IA: Moderate Na+ channel blockers (e.g., quinidine).
      • Class IB: Weak Na+ channel blockers, reducing effective refractory period (ERP) (e.g., lidocaine).
      • Class IC: Strong Na+ blockers with no effect on ERP (e.g., flecainide).
      • Class II: Beta-blockers that decrease AV conduction and inhibit phase 4 depolarization (e.g., metoprolol).
      • Class III: K+ channel blockers increasing ERP (e.g., amiodarone).
      • Class IV: Ca2+ channel blockers that increase ERP (e.g., verapamil).
    • Unclassified Drugs: Include digoxin, adenosine, and magnesium sulfate.

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    Description

    This quiz explores the phases of cardiac action potential, detailing the ion movements during each phase from resting state to repolarization. Understand the significance of Na+ and K+ in generating electrical activity in cardiac cells.

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