Cardiac muscle functions as a syncytium because a wave of depolarization, followed by contractions of the atria and ventricles(an all-or-none response), occurs when a uprathreshold stimulus is applied potentials, first depolarizing then re 十++++十++十 Autorhythmic cell ne(ms 十++++++十 升++++ 闺 十+++++十+ Autorhythmic cell Contractile cellCardiac muscle functions as a syncytium because a wave of depolarization, followed by contractions of the atria and ventricles (an all-or-none response), occurs when a uprathreshold stimulus is applied