Question 1

Which structure in the intrinsic cardiac conduction system is primarily responsible for initiating the heartbeat by generating action potentials?

Accepted Answer

Sinoatrial (SA) node

Question 2

What is the main function of gap junctions in cardiac muscle cells?

Accepted Answer

To allow action potentials to pass rapidly from cell to cell

Question 3

If the SA node fails to function, which part of the conduction system is most likely to take over as the pacemaker?

Accepted Answer

Atrioventricular (AV) node

Question 4

Which of the following correctly matches the cardiac conduction structure to its location in the heart?

Accepted Answer

Sinoatrial node: left atrium

Question 5

During the cardiac conduction pathway, which step occurs immediately after the action potential reaches the AV node?

Accepted Answer

100 ms delay

Question 6

Why does the AV node conduct impulses more slowly than the SA node?

Accepted Answer

To ensure the ventricles have enough time to fill with blood before they contract

Question 7

Which of the following best describes intrinsic conduction of the heart?

Accepted Answer

Cells within the heart can initiate and transmit action potentials without nervous system input

Question 8

Which structure is most directly responsible for allowing contraction of the ventricles to begin at the apex of the heart rather than in the septum closer to the AV node?

Accepted Answer

Purkinje fibers

Question 9

Which formula best represents the relationship between heart rate ($HR$), stroke volume ($SV$), and cardiac output ($CO$)?

Accepted Answer

$CO = HR 	imes SV$

Question 10

A patient has damage to the Purkinje fibers. Which of the following would most likely occur?

Accepted Answer

The ventricles would contract less efficiently

Question 11

Which nervous system division decreases heart rate by acting on the SA and AV nodes?

Accepted Answer

Parasympathetic nervous system

Question 12

If the vagus nerve is severed, what would be the expected effect on resting heart rate?

Accepted Answer

Resting heart rate would increase

Question 13

Which step in the cardiac conduction pathway is responsible for distributing the action potential throughout the ventricles?

Accepted Answer

Purkinje fibers

Question 14

Which of the following is a direct effect of sympathetic nervous system stimulation on the heart?

Accepted Answer

Increases heart rate

Question 15

Which of the following best explains why the heart can continue to beat after all nervous connections are severed?

Accepted Answer

The intrinsic conduction system generates its own action potentials

Question 16

Which of the following is the correct order of electrical conduction in the heart?

Accepted Answer

SA node → AV node → AV bundle → bundle branches → Purkinje fibers → ventricles

Question 17

Which of the following is a property of pacemaker cells in the SA node?

Accepted Answer

They rhythmically generate action potentials on their own

Question 18

A patient’s ECG shows a delay between atrial and ventricular contraction. Which part of the conduction system is most likely affected?

Accepted Answer

AV node

Question 19

Which of the following best describes the role of the AV bundle (Bundle of His) in cardiac conduction?

Accepted Answer

It transmits impulses from the AV node to the bundle branches

Question 20

Which equation describes the effect of autonomic nervous system input on heart rate ($HR$)?

Accepted Answer

$HR = HR_{intrinsic} + HR_{sympathetic} - HR_{parasympathetic}$

The Intrinsic Cardiac Conduction System: Structure, Function, and Regulation

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