Goosebumps are produced by contraction of which muscles?

Goosebumps are produced by contraction of which muscles?

• A. Contraction of pilomotor muscles causes hair to stand on end
• B. Contraction of skeletal muscles causes hair to stand on end
• C. Activation of sebaceous glands causes hair to stand on end
• D. Increased sweat production causes hair to stand on end

Answer: (A)

Hair standing on end happens when the tiny smooth muscles at the base of each hair follicle—the pilomotor muscles, also called arrector pili—contract. This autonomic, sympathetic response is triggered by cold, fear, or stress, pulling the hair upright and causing the skin to pucker into goosebumps. The other options don’t fit because skeletal muscles cause voluntary movement, while sebaceous glands secrete oil and sweat glands produce moisture; neither moves the hair shaft.

Hair standing on end happens when the tiny smooth muscles at the base of each hair follicle—the pilomotor muscles, also called arrector pili—contract. This autonomic, sympathetic response is triggered by cold, fear, or stress, pulling the hair upright and causing the skin to pucker into goosebumps. The other options don’t fit because skeletal muscles cause voluntary movement, while sebaceous glands secrete oil and sweat glands produce moisture; neither moves the hair shaft.