What is the typical sequence of heart conduction starting from the SA node?

The sequence starting from the SA node accurately reflects the normal conduction pathway of electrical impulses in the heart. Beginning with the SA node, which is located in the right atrium, the impulse is generated and spreads through the atria, causing them to contract and push blood into the ventricles.

Next, the electrical impulse travels to the AV node. The AV node acts as a gateway that briefly delays the conduction to allow the ventricles time to fill with blood from the atria before they contract. Following this delay, the impulse moves down to the Bundle of His, which is a pathway situated in the interventricular septum.

From the Bundle of His, the electrical signal diverges into the right and left bundle branches, which then lead to the Purkinje fibers. The Purkinje fibers distribute the impulse throughout the ventricles, leading to their contraction and thus enabling effective blood pumping from the heart.

This sequence is critical for maintaining a coordinated heartbeat and ensuring that the heart functions effectively. The other options do not correctly reflect the typical physiological pathway of the electrical impulse within the heart.