Which of these is a property of cardiac cells when transmitting impulses from one cell to another?

• A. Conductivity
• B. Automaticity
• C. Contractility
• D. Excitability

Answer: (A)

Conductivity is the property at play here. It’s the myocardium’s ability to propagate an electrical impulse from one cell to the next through gap junctions in the intercalated discs, so the depolarization wave sweeps across the heart and coordinates contraction. This cell-to-cell transmission is what lets the heartbeat stay synchronized as the impulse moves from the atria to the ventricles.

Automaticity is about impulses being generated spontaneously by pacemaker cells, not about transmission between cells. Excitability describes a cell’s ability to respond to a stimulus with an action potential, and contractility is the ability to shorten and generate force once stimulated. The scenario described focuses on how the impulse travels from cell to cell, which is conductivity.