What term describes the myocardium's ability to depolarize and contract as a single unit due to rapid, directional conduction through gap junctions?

• A. Functional syncytium
• B. Isolated myocardium
• C. Electrical decoupling
• D. Atrial kick

Answer: (A)

The term describes how the heart muscle works as a single functional unit thanks to gap junctions that allow ions to pass rapidly from one cell to the next. This rapid, directional conduction lets the myocardium depolarize and contract in unison, so the atrial and ventricular walls act like one coordinated mass rather than many isolated fibers. That coordinated, unitary contraction is what the functional syncytium captures. In contrast, ideas like isolated myocardium imply separateness, electrical decoupling would hinder spread of the impulse, and the atrial kick refers to an added contraction contribution, not the unified depolarization-and-contraction property.