Most Smooth Muscle Cells can CONTRACT WITHOUT Nervous Stimulation. Because most of its movements cannot be consciously controlled, Smooth Muscle is referred to as Involuntary Muscle.

Can rhythmically contract in response to pacemaker cells without stimulation from nerves?

The heart is a muscular organ which can contract in a rhythmic manner without direct stimulus from the nervous system because of the activity of pacemaker cells.

How does the heart contract without nervous system stimulation?

Cardiac muscle cells contract without stimulation by the central nervous system (contraction is myogenic) Cardiac muscle cells are branched, allowing for faster signal propagation and contraction in three dimensions. Cardiac muscles cells are not fused together, but are connected by gap junctions at intercalated discs.