Question

The following are structural components of the conducting system of the heart. 1. Purkinje fibers 2. AV bundle 3. AV node 4. SA node 5. bundle branches. What is the sequence in which excitation would move through this system?

A) 1, 4, 3, 2, 5
B) 3, 2, 4, 5, 1
C) 4, 3, 2, 5, 1
D) 4, 2, 3, 5, 1
E) 3, 5, 4, 2, 1

Answer 1

The correct sequence for excitation movement through the heart's conducting system is from the SA node, to the AV node, the AV bundle, the bundle branches, and finally to the Purkinje fibers, which is represented by the option C) 4, 3, 2, 5, 1.

Step-by-step explanation:

The sequence in which excitation would move through the structural components of the conducting system of the heart is best described as starting with the sinoatrial (SA) node, moving to the atrioventricular (AV) node, followed by the atrioventricular (AV) bundle (also known as the bundle of His), then to the bundle branches, and finally reaching the Purkinje fibers. Therefore, the correct answer is C) 4, 3, 2, 5, 1.

Here's how the conduction system operates during a heartbeat:

1. The SA node generates an electrical impulse, causing the atria to contract.
2. The impulse travels to the AV node where there is a brief delay, allowing the atria to empty their contents into the ventricles.
3. Following the delay, the impulse moves through the AV bundle and then into the right and left bundle branches.
4. Finally, the Purkinje fibers conduct the impulse throughout the ventricular myocardium, leading to ventricular contraction.