Final answer:
The myocytes make up single-unit smooth muscle and are connected by gap junctions that allow them to contract as a coordinated unit, crucial for the operation of hollow organs.
Step-by-step explanation:
The cells that compose single-unit smooth muscle are referred to as myocytes. Single-unit smooth muscle cells are connected by gap junctions which allows them to contract in a coordinated fashion as a whole unit, contrary to multiunit smooth muscle cells that lack these connections and contract individually. In single-unit smooth muscle, also known as visceral muscle, this coordinated contraction is crucial for the function of hollow organs, such as those in the digestive and urinary systems, ensuring that substances move steadily through the body. The spindle-shaped myocytes contain myofibrils composed of actin and myosin, which slide over one another to facilitate muscle contractions, even though these cells lack the striations found in skeletal muscles.