Which cells generate action potentials that spread throughout the myocardium causing the heart to contract as a single unit?

Which cells generate action potentials that spread throughout the myocardium causing the heart to contract as a single unit?

• A. Autorhythmic cells
• B. Cardiac myocytes
• C. Atrial cells
• D. Ventricular cells

Answer: (A)

Coordinated heartbeat depends on pacemaker/conduction cells that spontaneously generate electrical impulses and rapidly propagate them through the heart muscle, so the atrial and ventricular muscles contract together as one unit. These autorhythmic cells, found in the sinoatrial node and other parts of the conduction system, initiate each heartbeat and set the pace. Their impulses travel through gap junctions in the conducting pathways and myocardium, spreading quickly and synchronously to cause the entire heart muscle to contract in a coordinated sequence. Cardiac myocytes are the contractile cells that respond to this signal, not the source of the rhythm themselves. Atria and ventricular cells are types of contractile myocardium that contract when the impulse arrives, but they don’t spontaneously generate the initiating signal.

Coordinated heartbeat depends on pacemaker/conduction cells that spontaneously generate electrical impulses and rapidly propagate them through the heart muscle, so the atrial and ventricular muscles contract together as one unit. These autorhythmic cells, found in the sinoatrial node and other parts of the conduction system, initiate each heartbeat and set the pace. Their impulses travel through gap junctions in the conducting pathways and myocardium, spreading quickly and synchronously to cause the entire heart muscle to contract in a coordinated sequence. Cardiac myocytes are the contractile cells that respond to this signal, not the source of the rhythm themselves. Atria and ventricular cells are types of contractile myocardium that contract when the impulse arrives, but they don’t spontaneously generate the initiating signal.