The Pacemaker Action Potentials in the Heart

Multiple Choice

The pacemaker action potentials in the heart

A) are due to opposing actions of norepinephrine and acetylcholine.
B) are generated by the bundle of His.
C) depend on the gap junctions between the cells that make up the atria and those that make up the ventricles.
D) are due to spontaneous depolarization of the plasma membranes of modified cardiac muscle cells.
E) result from hyperpolarization of cells in the sinoatrial node.