Question 1

Which neurotransmitter is released by both sympathetic and parasympathetic preganglionic neurons at the autonomic ganglia?

Accepted Answer

Acetylcholine (ACh)

Question 2

A drug increases activation of cardiac $$\$$beta_1$$ receptors. Which of the following is the most likely effect on the heart?

Accepted Answer

Increased heart rate, increased contractility, and increased AV nodal conduction

Question 3

Which receptor is activated by acetylcholine (ACh) released from parasympathetic postganglionic neurons at cardiac targets?

Accepted Answer

Muscarinic M$$_2$$ receptor

Question 4

Which term describes the effect of sympathetic stimulation increasing the speed of electrical conduction through the AV node?

Accepted Answer

Positive dromotropy

Question 5

A patient experiences increased vagal activity. Which neurotransmitter and receptor are responsible for the decreased heart rate and slowed AV nodal conduction?

Accepted Answer

Acetylcholine acting on muscarinic M$$_2$$ receptors

Question 6

Which event directly triggers calcium-induced calcium release in a ventricular cardiomyocyte?

Accepted Answer

Entry of Ca$$^{2+}$$ through L-type Ca$$^{2+}$$ channels

Question 7

Compare the action potentials of pacemaker cells and contractile cardiomyocytes. Which ionic movement is primarily responsible for the rapid depolarization phase in each?

Accepted Answer

Ca$$^{2+}$$ influx in pacemaker cells; Na$$^+$$ influx in contractile cells

Question 8

During isovolumetric contraction in the cardiac cycle, what is the state of the heart valves and ventricular pressure?

Accepted Answer

Both AV and semilunar valves are closed; ventricular pressure rises

Question 9

A ventricle has an end-diastolic volume (EDV) of 145 mL and an end-systolic volume (ESV) of 60 mL. What is the stroke volume (SV)?

$$SV = EDV - ESV$$

Accepted Answer

$$SV = 85\ 	ext{mL}$$

Question 10

Which ECG feature represents ventricular depolarization?

Accepted Answer

QRS complex

Question 11

What causes the aortic valve to open during a normal cardiac cycle?

Accepted Answer

Ventricular pressure exceeds aortic pressure

Question 12

Which of the following best describes the Frank–Starling mechanism?

Accepted Answer

Increased ventricular filling leads to increased contraction force and stroke volume

Question 13

A patient has normal electrical activation of the ventricles, but a drug reduces Ca$$^{2+}$$ entry through L-type channels. What is the most likely effect?

Accepted Answer

Electrical activity remains normal, but contraction becomes weaker

Question 14

Which structure is the dominant pacemaker of the heart, initiating each normal heartbeat?

Accepted Answer

Sinoatrial (SA) node

Question 15

Which of the following best explains why the AV node delays electrical conduction from atria to ventricles?

Accepted Answer

To allow the ventricles to fill with blood before they contract

Question 16

Which equation correctly calculates cardiac output (CO)?

Accepted Answer

$$CO = SV 	imes HR$$

Question 17

A drug blocks M$$_2$$ receptors in the heart. What is the most likely effect on parasympathetic regulation of heart rate?

Accepted Answer

Parasympathetic activity will be unable to slow heart rate

Question 18

Which of the following is a major functional difference between autorhythmic and contractile cardiomyocytes?

Accepted Answer

Autorhythmic cells generate spontaneous electrical activity; contractile cells generate force

Question 19

Which structure in the cardiac conduction pathway is responsible for rapidly distributing electrical activation through the ventricular myocardium?

Accepted Answer

Purkinje fibers

Cardiac Physiology: Electrical Activity, Conduction, and Pumping

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