How does the heart control the rate at which it beats?
Heart rate is controlled by the sinoatrial node, the body's natural pacemaker.
Sinoatrial node or SA node is a specialized heart tissue capable of generating electrical signals. It is present in right atrium and has its own pacing rate.
The electrical impulses generated by SA node are conducted by the atrial tissue (right and left atria) and then through the AV (atrioventricular node) to the ventricles. This impulse is responsible for depolarization and systole.
Heart muscle is a type of striated muscle (involuntary muscle). Therefore, the activity of its pacemaker is also influenced by the sympathetic and parasympathetic activity of the nervous system.