Fibrillation happens when many different cells in the heart begin to act as pacemaker cells.

Hence, these cells generate the normal sinus rhythm and are called pacemaker cells as they directly control the heart rate.

This is a group of pacemaker cells which spontaneously depolarize to create an action potential.

Activity is initiated by the pacemaker cells (interstitial cells of Cajal).

The cardiac pacemaker cells of the sinoatrial node in the heart provide a good example.

The pre-botzinger complex also contains pacemaker cells which initiate spontaneous breathing.

The cells that create these rhythmical impulses are called pacemaker cells, and they directly control the heart rate.

There are three main stages in the generation of an action potential in a pacemaker cell.

In some cells, the membrane potential is always changing (such as cardiac pacemaker cells).

The depolarization rate and duration of the action potential in pacemaker cells is affected by autonomic nervous system activity.