Question

electrical activity is started at the sa node, which causes an action potential to spread through the heart through the ________.

cardiac cycle
blood flow
internal skeleton
conduction system

Explanation:

The SA node (sino - atrial node) is the heart's natural pacemaker. Electrical activity starts here and spreads through the heart's conduction system, which includes structures like the atrioventricular (AV) node, bundle of His, and Purkinje fibers, causing the heart to contract in an orderly manner. The cardiac cycle is the sequence of events in one heartbeat, blood flow is the movement of blood through the heart and body, and the internal skeleton has no role in electrical conduction in the heart.

Answer:

O conduction system