Which type of muscle tissue is involuntary and makes up the heart?

Cardiac muscle is the correct answer because it is a specialized type of involuntary muscle tissue that is exclusively found in the heart. This muscle tissue is unique in structure and function, allowing the heart to pump blood effectively throughout the body without conscious control. Unlike skeletal muscle, which is under voluntary control and enables movements such as walking or lifting, cardiac muscle operates autonomously and rhythmically, thanks to its inherent ability to generate electrical impulses.

Furthermore, cardiac muscle cells, also known as cardiomyocytes, are interconnected by intercalated discs, which facilitate synchronized contractions essential for maintaining a steady heartbeat. This structural characteristic distinguishes cardiac muscle from smooth muscle, which is also involuntary but found in various internal organs, and from skeletal muscle, which is voluntary. Thus, understanding the unique attributes of cardiac muscle elucidates why it is the specific type of muscle tissue that composes the heart.