MCAT Question A Day - 4/21/14

Arrector pili muscles are smooth muscles associated with hair follicles in the skin. When contracted, the muscles pull the hairs erect and “goose bumps” appear as the skin around the hair shafts slightly elevates. What stimulates the arrector pili muscles to contract?

A. Somatic motor neurons

B. Autonomic motor neurons

C. Exocrine secretions

D. Endocrine secretions

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