Emergency Medical Technician (EMT) Intermediate Practice Exam

What term describes the myocardium's ability to generate its own electrical impulses?

1. Excitability

2. Contractility

3. Automaticity

4. Conductivity

The correct answer is: Automaticity

The term that describes the myocardium's ability to generate its own electrical impulses is automaticity. This intrinsic property enables cardiac muscle cells, specifically pacemaker cells found in the sinoatrial (SA) node, to initiate electrical activity leading to heart contractions without requiring external stimulation from the nervous system. Automaticity is essential for maintaining a regular heartbeat and ensuring that the heart can respond appropriately to changes in the body’s needs, such as during exercise or stress. It allows the heart to self-regulate its rhythm and adapt to varying physiological demands. In contrast, excitability refers to the ability of myocardial cells to respond to stimuli, contractility describes the strength of myocardial contraction, and conductivity pertains to the ability of cardiac cells to transmit electrical impulses through the heart. While all these properties are crucial for heart function, it is automaticity that specifically addresses the heart's capacity to generate its own impulses independently.