Which muscle type is typically found lining internal organs and is involuntary?

Which muscle type is typically found lining internal organs and is involuntary?

• A. Cardiac Muscle
• B. Smooth Muscle
• C. Striated Muscle
• D. Skeletal Muscle

Answer: (B)

Smooth muscle is the tissue that lines the walls of hollow organs such as the stomach, intestines, bladder, and blood vessels. It operates under involuntary control, meaning you don’t consciously move it; its activity is governed by the autonomic nervous system and local factors. This muscle is non-striated and made of spindle-shaped cells, which allows it to produce slow, sustained contractions essential for moving contents through the organs (peristalsis) and for adjusting the diameter of lumens. By contrast, cardiac muscle forms the heart walls and is also involuntary but is striated with intercalated discs, while skeletal muscle is voluntary and striated, attached to bones. The combination of lining hollow organs, non-striated appearance, and involuntary control makes smooth muscle the correct choice.

Smooth muscle is the tissue that lines the walls of hollow organs such as the stomach, intestines, bladder, and blood vessels. It operates under involuntary control, meaning you don’t consciously move it; its activity is governed by the autonomic nervous system and local factors. This muscle is non-striated and made of spindle-shaped cells, which allows it to produce slow, sustained contractions essential for moving contents through the organs (peristalsis) and for adjusting the diameter of lumens. By contrast, cardiac muscle forms the heart walls and is also involuntary but is striated with intercalated discs, while skeletal muscle is voluntary and striated, attached to bones. The combination of lining hollow organs, non-striated appearance, and involuntary control makes smooth muscle the correct choice.