Smooth muscle cells are specialized cells found in the walls of hollow organs, such as the stomach, intestines, and blood vessels. Unlike skeletal muscle cells, which are under voluntary control, smooth muscle cells operate involuntarily, meaning they function automatically without conscious effort. They are responsible for various essential processes, including the movement of food through the digestive system and the regulation of blood flow. These cells are characterized by their spindle shape and lack of striations, which distinguishes them from other muscle types. Smooth muscle cells can contract and relax slowly, allowing for sustained contractions that help maintain functions like peristalsis in the digestive tract and vasodilation in blood vessels.