Which type of muscle cell has visible striations but is not under voluntary control?

Cardiac muscle is characterized by visible striations, which are alternating light and dark bands that result from the regular arrangement of actin and myosin filaments within the muscle fibers. These striations are similar to those found in skeletal muscle, but unlike skeletal muscle, cardiac muscle is not under voluntary control. Instead, it is regulated by the autonomic nervous system and hormones, allowing it to function involuntarily. This means that the muscles of the heart contract rhythmically and continuously without conscious control, which is essential for maintaining a steady blood flow throughout the body.

Cardiac muscle cells also have unique features that distinguish them from both skeletal muscle (which is voluntary) and smooth muscle (which is non-striated and also involuntary). Cardiac muscle fibers are interconnected through specialized junctions called intercalated discs, which help synchronize contractions of the heart muscle, while smooth muscle cells are found in various organs and do not exhibit striations. The presence of striations combined with the involuntary nature of cardiac muscle makes it a unique tissue type critical to the cardiovascular system.