What part of the heart generates rhythmical impulses spontaneously?

The intrinsic impulse conducting system of the heart is responsible for generating rhythmical impulses spontaneously. This system consists of specialized cardiac tissue that includes structures such as the sinoatrial (SA) node, atrioventricular (AV) node, and the bundle of His, along with the Purkinje fibers. The SA node is often referred to as the natural pacemaker of the heart because it initiates electrical impulses that trigger each heartbeat, regulating the heart rate and rhythm without relying on external stimuli.

These impulses spread through the atria and then through the ventricles, ensuring synchronized contraction and efficient blood pumping throughout the body. This automaticity is a key characteristic of the heart’s conduction system, distinguishing it from other muscle contractions in the body that are primarily controlled by the nervous system or voluntary control.

The autonomic nervous system, while it plays a vital role in modulating heart rate and force of contraction through sympathetic and parasympathetic inputs, does not generate rhythmic impulses by itself. Cardiac muscle fibers are responsible for the contraction of the heart but do not initiate their own electrical activity, and coronary arteries are involved in supplying blood to the heart muscle but do not participate in generating impulses.