Certified Rhythm Analysis Technician (CRAT) Practice Exam 2025 - Free CRAT Practice Questions and Study Guide

Automaticity refers specifically to the heart's ability to initiate an electrical impulse on its own, without requiring any external stimulation. This intrinsic property is primarily associated with the specialized pacemaker cells found in the sinoatrial (SA) node of the heart. These cells generate action potentials independently, which can subsequently propagate through the heart muscle, leading to coordinated contractions.

In contrast, the other options describe important aspects of cardiac function but do not encapsulate the essence of automaticity. For instance, the ability to receive and transmit an electrical impulse refers more to conduction rather than initiation. The capacity of the heart muscle to contract in response to an electrical stimulus pertains to contractility, which is not the same as creating the impulse itself. Lastly, while heart muscle cells do respond to impulses, automaticity emphasizes the heart’s ability to create those impulses autonomously. Thus, the definition that best captures the concept of automaticity is the ability of the heart to initiate an electrical impulse without external stimulation.