ANATOMY

Detailed explanation-1: -Cardiac muscle cells are located in the walls of the heart, appear striped (striated), and are under involuntary control. Smooth muscle fibers are located in walls of hollow visceral organs (such as the liver, pancreas, and intestines), except the heart, appear spindle-shaped, and are also under involuntary control.

Detailed explanation-2: -Smooth muscle, found in the walls of the hollow internal organs such as blood vessels, the gastrointestinal tract, bladder, and uterus, is under control of the autonomic nervous system. Smooth muscle cannot be controlled consciously and thus acts involuntarily.

Detailed explanation-3: -Cardiac muscles are said to be involuntary because they are not controlled by our will. These muscles are found in heart and are the only muscles which work throughout the life without getting tired or fatigue.

Detailed explanation-4: -Cardiac muscle, like skeletal muscle, is made up of sarcomeres that allow for contractility. However, unlike skeletal muscle, cardiac muscle is under involuntary control. The cardiac muscle is responsible for the contractility of the heart and, therefore, the pumping action.

Detailed explanation-5: -Cardiac muscle cells are striated as they have dark bands and light bands (striations). The working of these muscles is not under the conscious will of the organism, hence these are called involuntary muscles.