Introduction: Hemodynamics and electrophysiology form the foundation of cardiac physiology for B. Pharm students. This topic covers cardiac output, stroke volume, preload, afterload, vascular resistance, pressure-volume loops, and the molecular basis of action potentials in pacemaker and ventricular cells. Key concepts include ion channels (Na+, Ca2+, K+), conduction pathways (SA node, AV node, Purkinje), ECG interpretation, refractory periods, arrhythmia mechanisms, and pharmacologic modulation by antiarrhythmics and inotropes. Mastery of these principles links drug action to cardiac function, aiding rational therapeutics. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What primarily determines stroke volume under normal physiologic conditions?
- Heart rate
- Preload (end-diastolic volume)
- Systemic vascular resistance
- Atrial fibrillation
Correct Answer: Preload (end-diastolic volume)
Q2. Which phase of the ventricular action potential corresponds to rapid repolarization?
- Phase 0
- Phase 1
- Phase 2
- Phase 3
Correct Answer: Phase 3
Q3. The pacemaker current (If) that contributes to spontaneous depolarization in the SA node is primarily carried by which ions?
- Sodium and potassium
- Calcium only
- Sodium only
- Chloride and bicarbonate
Correct Answer: Sodium and potassium
Q4. On a pressure-volume loop, an increase in afterload most directly shifts which part of the loop?
- Rightward shift of end-diastolic volume
- Upward and leftward shift of end-systolic pressure
- Downward shift of the isovolumetric contraction line
- Flattening of the diastolic filling curve
Correct Answer: Upward and leftward shift of end-systolic pressure
Q5. Which ECG interval primarily reflects atrioventricular (AV) conduction time?
- QRS duration
- PR interval
- QT interval
- ST segment
Correct Answer: PR interval
Q6. Which ion channel blockade is the main mechanism of Class III antiarrhythmic drugs?
- Fast sodium channel blockade
- Beta-adrenergic receptor blockade
- Delayed rectifier potassium channel blockade
- Calcium channel T-type blockade
Correct Answer: Delayed rectifier potassium channel blockade
Q7. In ventricular myocytes, which channel predominates during the plateau (phase 2) of the action potential?
- Fast sodium channels
- L-type calcium channels
- Inward rectifier potassium channels
- Transient outward potassium channels
Correct Answer: L-type calcium channels
Q8. The Frank–Starling law describes the relationship between:
- Afterload and contractility
- Preload and stroke volume
- Heart rate and myocardial oxygen consumption
- Systemic vascular resistance and cardiac output
Correct Answer: Preload and stroke volume
Q9. Which parameter is a direct clinical estimate of left ventricular contractility?
- End-diastolic volume
- Maximum dP/dt during isovolumetric contraction
- Central venous pressure
- Pulse pressure
Correct Answer: Maximum dP/dt during isovolumetric contraction
Q10. Which change on ECG is most characteristic of acute transmural myocardial ischemia?
- PR segment depression
- ST segment elevation
- Prolonged QT without ST change
- Low voltage QRS only
Correct Answer: ST segment elevation
Q11. Which law explains how wall tension increases with chamber radius and pressure, contributing to myocardial oxygen demand?
- Frank–Starling law
- Laplace’s law
- Bernoulli’s principle
- Ohm’s law
Correct Answer: Laplace’s law
Q12. Which of the following best describes the effective refractory period (ERP) in cardiac tissue?
- Time during which a stronger-than-normal stimulus produces a normal action potential
- Interval when heart is completely electrically silent
- Period when a new action potential cannot be initiated regardless of stimulus strength
- Time when only atrial tissue is refractory
Correct Answer: Period when a new action potential cannot be initiated regardless of stimulus strength
Q13. Which ion exchanger or pump is crucial for removing cytosolic Ca2+ during diastolic relaxation of cardiomyocytes?
- Sodium-calcium exchanger (NCX) and SERCA pump
- Voltage-gated sodium channel
- Na+/K+ ATPase only
- Cl−/HCO3− antiporter
Correct Answer: Sodium-calcium exchanger (NCX) and SERCA pump
Q14. A shortened PR interval with a delta wave on ECG suggests which condition?
- AV nodal block
- Wolff–Parkinson–White syndrome (pre-excitation)
- Hyperkalemia
- Bundle branch block
Correct Answer: Wolff–Parkinson–White syndrome (pre-excitation)
Q15. Which autonomic effect increases heart rate and increases conduction velocity through the AV node?
- Increased vagal tone
- Increased sympathetic tone via beta-1 receptors
- Increased parasympathetic via muscarinic receptors
- Increased baroreceptor firing
Correct Answer: Increased sympathetic tone via beta-1 receptors
Q16. Which measurement is used to calculate mean arterial pressure (MAP) approximately?
- (Systolic + Diastolic) / 2
- Diastolic + 1/3(Systolic − Diastolic)
- Systolic − Diastolic
- Pulse pressure × heart rate
Correct Answer: Diastolic + 1/3(Systolic − Diastolic)
Q17. Re-entry is a common arrhythmia mechanism. Which condition favors re-entry circuits?
- Uniform conduction velocity and short refractory period
- Region with unidirectional block and slowed conduction around an excitable pathway
- Complete homogenous refractoriness across tissue
- Isolated SA node automaticity only
Correct Answer: Region with unidirectional block and slowed conduction around an excitable pathway
Q18. Beta-blockers reduce myocardial oxygen demand primarily by which mechanisms?
- Increasing heart rate and contractility
- Reducing heart rate, contractility, and blood pressure
- Vasodilation of coronary microcirculation only
- Blocking L-type calcium channels in cardiomyocytes
Correct Answer: Reducing heart rate, contractility, and blood pressure
Q19. Which ECG change is commonly seen with hyperkalemia as it progresses?
- ST elevation followed by Q waves
- Peaked T waves, then widened QRS, then sine-wave pattern
- Prolonged PR interval then narrow QRS complex
- Inverted P waves only
Correct Answer: Peaked T waves, then widened QRS, then sine-wave pattern
Q20. Class I antiarrhythmics act primarily by blocking which target?
- Beta-adrenergic receptors
- Voltage-gated sodium channels
- Delayed rectifier potassium channels
- L-type calcium channels
Correct Answer: Voltage-gated sodium channels
Q21. Which vessel contributes most to total peripheral resistance (TPR) under resting conditions?
- Large elastic arteries
- Arterioles
- Capillaries
- Venules
Correct Answer: Arterioles
Q22. Which statement best describes the role of the AV node during rapid atrial arrhythmias?
- It always conducts 1:1 to the ventricles
- It filters impulses and can limit ventricular rate due to its slow conduction and longer refractory period
- It speeds up conduction to protect ventricles
- It generates new pacemaker activity faster than SA node
Correct Answer: It filters impulses and can limit ventricular rate due to its slow conduction and longer refractory period
Q23. In heart failure with reduced ejection fraction, which compensatory change initially preserves cardiac output?
- Decreased preload via venodilation
- Increased sympathetic activation raising heart rate and contractility
- Primary decrease in afterload
- Immediate myocardial regeneration
Correct Answer: Increased sympathetic activation raising heart rate and contractility
Q24. Which component of the ECG corresponds to ventricular depolarization?
- P wave
- QRS complex
- T wave
- U wave
Correct Answer: QRS complex
Q25. Cardiac output equals:
- Stroke volume × heart rate
- Mean arterial pressure × systemic vascular resistance
- Preload × afterload
- Pulse pressure × ejection fraction
Correct Answer: Stroke volume × heart rate
Q26. Which ion current is primarily responsible for the rapid upstroke (phase 0) in ventricular myocytes?
- Slow inward calcium current (T-type)
- Fast sodium current (INa)
- Funny current (If)
- Delayed rectifier potassium current
Correct Answer: Fast sodium current (INa)
Q27. Which physiologic change will increase venous return to the heart?
- Reduced blood volume
- Increased intrathoracic pressure during positive-pressure ventilation
- Skeletal muscle pump during exercise
- Venous dilation due to histamine release
Correct Answer: Skeletal muscle pump during exercise
Q28. Torsades de pointes is linked to prolongation of which ECG interval?
- PR interval
- QRS duration
- QT interval
- ST segment only
Correct Answer: QT interval
Q29. Which of the following increases contractility (positive inotropy) via intracellular signaling?
- Beta-1 stimulation increasing cAMP and L-type Ca2+ channel activity
- Muscarinic M2 activation decreasing cAMP
- Blockade of SERCA function
- Inhibition of RyR channel opening
Correct Answer: Beta-1 stimulation increasing cAMP and L-type Ca2+ channel activity
Q30. Which description best fits the sinoatrial (SA) node compared with ventricular myocardium?
- Faster upstroke velocity and more negative resting membrane potential
- Slower upstroke velocity, more positive maximum diastolic potential, and automaticity due to If and Ca2+ currents
- Identical ion channel complement and action potential shape
- No influence of autonomic neurotransmitters
Correct Answer: Slower upstroke velocity, more positive maximum diastolic potential, and automaticity due to If and Ca2+ currents
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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