What type of muscle is primarily responsible for involuntary actions, such as digestion?

Smooth muscle is primarily responsible for involuntary actions, such as digestion. This type of muscle is not under conscious control and is found in various organs and systems within the body, including the gastrointestinal tract, where it aids in the movement of food through peristalsis. Smooth muscle fibers are not striated, allowing for sustained contractions without fatigue, which is essential for functions like propelling food through the digestive system.

Skeletal muscle, on the other hand, is responsible for voluntary movements and is under conscious control, allowing you to perform activities like walking or lifting weights. Cardiac muscle, while also involuntary, is specific to the heart and its primary function is to pump blood throughout the body. Striated muscle is a general term often used to describe skeletal and cardiac muscles due to their striped appearance, but it does not encompass the functions of smooth muscle. Thus, the correct answer emphasizes the role of smooth muscle in involuntary physiological processes.