Question

Arrange the following steps in the pathway of the conduction system of the heart in the correct sequence:

1) AV node
3) AV bundle & bundle branches
2) SA node
4) Purkinje fibers

a. 3, 1, 2, 4
b. 2, 1, 3, 4
c. 1, 2, 3, 4
d. 1, 3, 2, 4

Answer 1

The correct sequence for the conduction system of the heart begins with the SA node initiating an action potential, followed by a pause at the AV node, then transmission through the atrioventricular bundle to the Purkinje fibers, which causes the ventricles to contract.

Step-by-step explanation:

The conduction system of the heart is responsible for the sequence of events that generates a heartbeat. This system includes the sinoatrial (SA) node, the atrioventricular (AV) node, the atrioventricular bundle (bundle of His), the right and left bundle branches, and the Purkinje fibers.

The correct sequence of the conduction system during a heartbeat is as follows:

1. The SA node initiates the action potential, which spreads across the atria.
2. After reaching the AV node, there is a delay to allow the atria to finish pumping blood into the ventricles.
3. The impulse is transmitted to the atrioventricular bundle and travels down the right and left bundle branches.
4. It reaches the Purkinje fibers and spreads to the ventricular muscle, causing the ventricles to contract.

This sequence ensures that the atria contract slightly before the ventricles, allowing for efficient pumping of the blood through the heart and into the systemic circulation.