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

The type of muscle that is involuntary and found in the heart is cardiac muscle. This muscle tissue has a unique structure and function, characterized by its striated appearance, which is similar to skeletal muscle. However, unlike skeletal muscle, which is under voluntary control, cardiac muscle operates involuntarily. This means it contracts and controls the heartbeat autonomously, without conscious effort.

Cardiac muscle cells, known as cardiomyocytes, are interconnected by intercalated discs, allowing for synchronized contractions that are essential for maintaining a consistent and effective heartbeat. This coordinated action is crucial for pumping blood throughout the body, ensuring the delivery of oxygen and nutrients to tissues and the removal of waste products.

Skeletal muscle, while striated, is under voluntary control, allowing for movements of the skeleton. Smooth muscle, which is involuntary, is found in the walls of hollow organs like the intestines and blood vessels, but it does not have the striated appearance of cardiac or skeletal muscle. Striated, in this context, generally refers to both skeletal and cardiac muscle, but since the question specifically asks for the muscle type found in the heart, cardiac is the correct answer.