Follow an impulse from the SA node to the Purkinje fibers (just
indicate the pathway and name appropriate nodes/bundles). Be sure
to indicate when the atria and ventricles contract. Once you get to
the Purkinje fibers, describe what will happen to adjacent
contractile cells, in terms of ion flow and how it affects
contraction and relaxation. Be specific in describing the channels,
and mention the terms depolarization, plateau, repolarization,
absolute refractory. You do NOT need to mention specific voltage
values. How is cardiac muscle prevented from reaching tetany?