How do smooth muscle and skeletal muscle differ in control and appearance?

• A. Smooth muscle is voluntary and striated
• B. Smooth muscle is involuntary and non-striated
• C. Skeletal muscle is involuntary and non-striated
• D. Skeletal muscle is voluntary and striated

Answer: (B)

Control and appearance differentiate smooth and skeletal muscle. Smooth muscle is controlled involuntarily by the autonomic nervous system and lacks visible stripes, or striations, because its contractile proteins aren’t organized into the regular sarcomeres seen in skeletal muscle. This setup enables slow, sustained contractions that occur in the walls of hollow organs and blood vessels. Skeletal muscle, in contrast, is under voluntary control through the somatic nervous system and is striated, with clear bands from organized sarcomeres, allowing quick, forceful movements that move the skeleton. The statement that smooth muscle is involuntary and non-striated best captures the two features that distinguish smooth muscle from skeletal muscle. The other options either mix up control or appearance for smooth muscle or describe skeletal muscle in a way that doesn’t highlight the contrast.