Which type of muscle tissue is involuntary and found in the walls of the heart?

The type of muscle tissue that is involuntary and found in the walls of the heart is cardiac muscle. Cardiac muscle is specifically adapted for the unique demands of the heart, allowing it to contract rhythmically and continuously without conscious control. This involuntary action is crucial for maintaining a consistent heartbeat and ensuring adequate blood circulation throughout the body.

Cardiac muscle fibers are striated, similar to skeletal muscle, but they have a distinct structure that enables them to interconnect through specialized junctions known as intercalated discs. This arrangement facilitates coordinated contractions of the heart, making it efficient in pumping blood. The involuntary nature of cardiac muscle means that its contractions are regulated by the autonomic nervous system and hormonal signals rather than by voluntary control.

In contrast, skeletal muscle is under voluntary control and is used for movements of the body, while smooth muscle, which also operates involuntarily, is found in the walls of hollow organs like the intestines and blood vessels, not the heart. Striated muscle is a broad term that refers to both skeletal and cardiac muscles, but it does not specifically identify the involuntary nature associated with cardiac muscle.