Question 1

Which structure in the intrinsic cardiac conduction system is primarily responsible for initiating the electrical signal that sets the heart's rhythm?

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 feature of cardiac tissue allows for the rapid spread of action potentials through the heart?

Accepted Answer

Gap junctions

Question 5

Which statement best describes intrinsic conduction of the heart?

Accepted Answer

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

Question 6

Which answer choice below correctly matches the cardiac conduction structure to where it’s found in the heart?

Accepted Answer

Sinoatrial node: left atrium.

Question 7

The AV node has fewer gap junctions than the SA node, leading to slower conduction. How does this slower conduction help the heart function?

Accepted Answer

Ensures that the ventricles have enough time to fill with blood before they contract.

Question 8

What is the primary function of the pacemaker cells in the SA node in the heart?

Accepted Answer

Rhythmic generation of action potentials.

Question 9

Which structure or structures are 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 10

Which of the following best describes the pathway of electrical conduction in the heart?

Accepted Answer

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

Question 11

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

Accepted Answer

$$CO = HR 	imes SV$$

Question 12

If the sympathetic nervous system is activated, what is the expected effect on heart rate?

Accepted Answer

Heart rate increases.

Question 13

Which part of the cardiac conduction system is responsible for distributing the action potential throughout the ventricles, leading to their contraction?

Accepted Answer

Purkinje fibers

Question 14

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

Accepted Answer

100 ms delay occurs before the impulse moves to the AV bundle.

Question 15

Which of the following statements about the conduction system of the heart is correct?

Accepted Answer

The Purkinje fibers stimulate ventricular contraction.

Question 16

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

Accepted Answer

The ventricles would contract in a disorganized manner.

Question 17

Which of the following best explains why there are no gap junctions between cardiomyocytes of the atria and ventricles?

Accepted Answer

To prevent simultaneous contraction of atria and ventricles.

Question 18

Which nervous system division is responsible for decreasing heart rate?

Accepted Answer

Parasympathetic nervous system

Question 19

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

Accepted Answer

Resting heart rate would increase.

Question 20

Which of the following is the correct order of events in the cardiac conduction pathway?

Accepted Answer

SA node → AV node → AV bundle → Bundle branches → Purkinje fibers → Ventricles contract

The Intrinsic Cardiac Conduction System and Control of Heart Rate

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