CVS Practice Test 2025 - Free CVS Practice Questions and Study Guide

The correct term for the ability of cardiac tissue to demonstrate spontaneous phase 4 depolarization is automaticity. Automaticity refers to the intrinsic property of certain cardiac cells, such as those found in the sinoatrial (SA) node, to generate electrical impulses without external stimulation. This spontaneous depolarization occurs during phase 4 of the cardiac action potential and is crucial for maintaining the heart's natural rhythm.

Automaticity allows the heart to function independently of the nervous system and helps ensure that it can respond to changes in the body's physiological requirements. For example, during exercise, the increased heart rate is partly due to the enhanced automaticity of pacemaker cells.

Understanding automaticity highlights the specialized nature of cardiac tissue compared to other muscle types, where such spontaneous activity is not present. Other terms like refractoriness, cardiac excitability, and conductivity refer to different cardiac properties. Refractoriness relates to the recovery period after depolarization, excitability refers to how responsive cardiac cells are to stimulation, and conductivity describes the speed at which electrical impulses are transmitted through the cardiac tissue.