Question 1

Which neurotransmitter is released by sympathetic postganglionic fibers at the cardiac target tissue, and which receptor does it primarily bind to?

Accepted Answer

Norepinephrine; beta-1 adrenergic receptor

Question 2

A patient is given a drug that selectively blocks muscarinic receptors in the heart. What is the most likely effect on heart rate and why?

Accepted Answer

Heart rate increases because parasympathetic inhibition is blocked

Question 3

Which of the following best describes the difference between autorhythmic and contractile cardiomyocytes?

Accepted Answer

Autorhythmic cells generate action potentials spontaneously, while contractile cells require external stimulation

Question 4

Trace the normal pathway of electrical conduction through the heart. Which sequence is correct?

Accepted Answer

SA node → AV node → Bundle of His → Purkinje fibers

Question 5

Which ionic movement is primarily responsible for the rapid depolarization phase in contractile cardiomyocytes?

Accepted Answer

Influx of Na$$^+$$

Question 6

How does increased sympathetic stimulation affect pacemaker cell activity and heart rate?

Accepted Answer

It increases the slope of pacemaker potential, speeding up heart rate

Question 7

During excitation–contraction coupling in cardiac muscle, which event directly triggers calcium-induced calcium release from the sarcoplasmic reticulum?

Accepted Answer

Entry of Ca$$^{2+}$$ through L-type channels during the action potential

Question 8

A patient with heart failure has reduced Ca$$^{2+}$$ availability in contractile cardiomyocytes. What is the most likely effect on cardiac contractile force?

Accepted Answer

Contractile force decreases because less Ca$$^{2+} is $$available for cross-bridge formation

Question 9

Which ECG wave corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 10

During the cardiac cycle, which event occurs when ventricular pressure exceeds atrial pressure?

Accepted Answer

Atrioventricular (AV) valves close

Question 11

Given an end-diastolic volume (EDV) of 120 mL and an end-systolic volume (ESV) of 50 mL, calculate the stroke volume (SV) using the formula $$SV = EDV - ESV.$$

Accepted Answer

SV = 70 mL

Question 12

A patient has a heart rate (HR) of 80 beats per minute and a stroke volume (SV) of 65 mL. Calculate the cardiac output (CO) using $$CO = HR 	imes SV.$$

Accepted Answer

$$CO = 5200\ 	ext{mL/min}$$

Question 13

Which scenario would most likely increase stroke volume according to the Frank–Starling mechanism?

Accepted Answer

Increased ventricular filling (preload)

Question 14

If a patient experiences increased sympathetic activity, which of the following changes would you expect in cardiac output, assuming all other factors remain constant?

Accepted Answer

Cardiac output increases due to increased heart rate and contractility

Question 15

A patient is experiencing bradycardia (slow heart rate) due to excessive parasympathetic stimulation. Which neurotransmitter and receptor are most likely involved?

Accepted Answer

Acetylcholine; muscarinic receptor

Question 16

Which of the following best explains why the AV node slows electrical conduction between the atria and ventricles?

Accepted Answer

To allow time for ventricular filling before contraction

Question 17

A patient with a mutation that impairs L-type Ca$$^{2+}$$ channels in contractile cardiomyocytes would most likely experience which effect?

Accepted Answer

Reduced Ca$$^{2+}$$ entry, leading to weaker cardiac contractions

Question 18

Which of the following is a correct integration of autonomic regulation, electrical activity, and cardiac mechanics in a scenario where a person suddenly stands up?

Accepted Answer

Sympathetic activity increases, raising heart rate and contractility to maintain blood pressure and cardiac output

Question 19

Which of the following best describes the effect of increased preload on the cardiac cycle?

Accepted Answer

Increased preload leads to greater ventricular filling, which increases stroke volume via the Frank–Starling mechanism

Cardiovascular Physiology: Regulation, Electrical Activity, and Cardiac Output

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