Answer:
The correct answer is: automaticity.
Explanation:
Cardiac muscle has several properties. These properties are: automaticity (given by the pacemaker cells), conductivity (meaning that each cardiac cell can transmit the electrical impulse to the next cardiac cells), contractility (like other types of muscles, cardiac muscle cells can contract), and irritability (each cell can contract on its own without the external stimuli).
Cardiac pacemaker cells are the ones with the capacity to initiate the electrical impulse by creating rhythmic impulses called action potentials, and thus directly regulating heart rate.
Pacemaker cells are located in the sinoatrial (SA) node, in the upper portion of the right atrial wall. In these cells, depolarization of the cardiac muscle begins, and the electrical impulse generated by it is transmitted to the atrioventricular (AV) node, the His bundle and then the Purkinje fibers - this order of events is necessary for the correct contraction of the heart to occur. All of these structures are part of the Conduction System of the heart.
