What is a primary characteristic of cardiac muscle?

Cardiac muscle is primarily characterized by its striated appearance, which is a direct result of its unique structure and organization of actin and myosin filaments. This striation is similar to that seen in skeletal muscle, but cardiac muscle is distinct because it is involuntary in nature. The striations allow for coordinated contractions, essential for the heart's function in pumping blood throughout the body.

While skeletal muscle exhibits voluntary control and non-striated muscle is found in various types of involuntary muscles such as those in the digestive tract, cardiac muscle operates autonomously, regulated by the heart's intrinsic conduction system. Its location is also specific, found only in the heart, and not in the limbs, making the striated appearance the defining feature of cardiac muscle.