Question 1

Which structure in the mammalian heart acts as the primary pacemaker, initiating the electrical signal that triggers heart contraction, as shown in the first panel of the image?

Accepted Answer

Sinoatrial (SA) node

Question 2

What is the main function of the AV node in the cardiac conduction system, as depicted in the second panel of the image?

Accepted Answer

It delays the electrical signal to allow the atria to finish contracting before the ventricles contract.

Question 3

If the bundle branches (third panel) are damaged, which of the following is the most likely consequence?

Accepted Answer

The ventricles will contract in an uncoordinated manner.

Question 4

Which sequence correctly describes the path of electrical conduction through the mammalian heart as illustrated in the image?

Accepted Answer

SA node → AV node → Bundle branches → Purkinje fibers

Question 5

The ECG trace shown below each heart diagram in the image represents electrical activity in the heart. What does the sharp peak in the ECG correspond to?

Accepted Answer

Ventricular contraction

Question 6

Which of the following best explains why the electrical signal is delayed at the AV node (second panel)?

Accepted Answer

To allow the ventricles to fill completely with blood before they contract

Question 7

If the SA node fails to function, which part of the heart can take over as a secondary pacemaker, albeit at a slower rate?

Accepted Answer

AV node

Question 8

Which of the following statements about the Purkinje fibers (fourth panel) is correct?

Accepted Answer

They rapidly conduct the electrical signal throughout the ventricles, ensuring coordinated contraction.

Question 9

A patient’s ECG shows a prolonged interval between the P wave and the QRS complex. Which part of the conduction system is most likely malfunctioning?

Accepted Answer

AV node

Question 10

Which of the following best describes the role of the heart apex in the conduction system, as shown in the third panel?

Accepted Answer

It is the location where the bundle branches deliver the signal to the Purkinje fibers for ventricular contraction.

Chapter 17: Circulation and Gas Exchange: Structure and Function in Animals

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