Which body structure is made up of smooth muscle?

Which body structure is made up of smooth muscle?

• A. Heart
• B. Stomach
• C. Brain
• D. Bone

Answer: (B)

Smooth muscle is involuntary, non‑striated muscle found in the walls of hollow organs and vessels, where it propels contents through peristalsis and regulates internal flow. The stomach contains a muscularis externa made up of smooth muscle so its contractions mix and move food (chyme). In contrast, the heart is built from cardiac muscle, which is striated and specialized for rhythmic pumping; the brain comprises nervous tissue (neurons and glia), and bone is mineralized connective tissue. Therefore, the structure made up of smooth muscle is the stomach.

Smooth muscle is involuntary, non‑striated muscle found in the walls of hollow organs and vessels, where it propels contents through peristalsis and regulates internal flow. The stomach contains a muscularis externa made up of smooth muscle so its contractions mix and move food (chyme). In contrast, the heart is built from cardiac muscle, which is striated and specialized for rhythmic pumping; the brain comprises nervous tissue (neurons and glia), and bone is mineralized connective tissue. Therefore, the structure made up of smooth muscle is the stomach.