What feature distinguishes pacemaker cardiac cells from other myocardial cells? Pacemaker cells: A. require a stimulus from the vagus nerve in order to reach threshold, myocar- dial cells do not. B. reach threshold with much weaker stimuli than myocardial cells. C. have gap junctions, while myocardial cells do not. D. spontaneously generate action potentials, while myocardial cells do not.
Option D. Pacemaker cells (typically withinside the SA node) generate action poten- tials 80–100 times per minute even with out neural enter. Neural enter will slow or increase this rate. Myocardial cells aren't autorhythmic.
