Question

question 10 1 pts which part of the heart experiences the first contraction of a heartbeat? ventricles septum valves atria

Explanation:

The cardiac cycle starts with the contraction of the atria. The sino - atrial (SA) node, the heart's natural pacemaker, is located in the right atrium and initiates the electrical impulse that causes the atria to contract first, pumping blood into the ventricles.

Answer:

D. atria