MICROANATOMY

Detailed explanation-1: -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 differs from skeletal muscle in a variety of ways, perhaps the most important being its ability to be contracted and controlled involuntarily. The nervous system can use smooth muscle to tightly regulate many of the body’s subsystems for life with no thought from the user.

Detailed explanation-3: -The muscles whose functioning cannot be controlled are called involuntary muscles. They are spindle-shaped muscles. These are uninucleated. They are mainly regulated by the autonomic nervous system (ANS).