What type of muscle is classified as involuntary and non-striated?

Smooth muscle is classified as involuntary and non-striated, which is key to its function and characteristics. Unlike skeletal muscle, which is striated and under voluntary control, smooth muscle operates automatically and is found in various organs, such as the digestive tract, blood vessels, and the uterus. This involuntary nature allows smooth muscle to contract and relax in response to internal body signals and autonomic nervous system regulation without conscious effort.

The lack of striations in smooth muscle cells is due to the arrangement of muscle fibers. In contrast, cardiac muscle, while also involuntary, is striated and found only in the heart, with distinct structural and functional characteristics compared to smooth muscle. Skeletal muscle, on the other hand, is striated and under voluntary control, enabling precise movements. Striated muscle is a general term that encompasses both skeletal and cardiac muscle, but does not include smooth muscle. This distinction highlights why smooth muscle is the correct answer to the question.