What is the unique property of myocardial cells to generate a discharge without nerve stimulation called?

The unique property of myocardial cells to generate a discharge without nerve stimulation is referred to as automaticity. This characteristic allows certain cells within the heart, particularly in the sinoatrial (SA) node, to spontaneously generate electrical impulses that lead to contraction. Automaticity is crucial for maintaining the heart's rhythmic beating and ensuring proper blood flow throughout the body.

Other terms like contractility relate to the ability of heart muscle fibers to shorten and generate force when stimulated, while excitability refers to the ability of the cardiac cells to respond to stimuli, and conductivity is the capacity of cardiac tissue to propagate electrical impulses. These properties are essential for heart function but do not specifically describe the ability to generate impulses independently of nervous system input. Thus, automaticity is the correct term that uniquely defines the heart's capability to initiate its own electrical signal.