What is the function of the arrector pili muscle?

What is the function of the arrector pili muscle?

• A. To nourish hair follicles
• B. To contract and cause hair to stand upright (goosebumps)
• C. To secrete sebum
• D. To control hair pigment

Answer: (B)

The arrector pili muscle is a tiny smooth muscle attached to each hair follicle that responds to the autonomic nervous system. When it contracts, it pulls the hair follicle upright, causing the hair to stand up and producing goosebumps. This piloerection is a reflex we experience in cold or fear and it serves mainly to create a layer of air for insulation and to make the hair appear larger in animals. This muscle doesn’t nourish hair follicles—that’s provided by blood supply to the follicle and the hair papilla. It doesn’t secrete sebum—that’s the job of the sebaceous glands. It also doesn’t control hair pigment—that pigment comes from melanocytes in the hair matrix. So the function being tested is the contraction of the arrector pili leading to hair standing upright, i.e., goosebumps.

The arrector pili muscle is a tiny smooth muscle attached to each hair follicle that responds to the autonomic nervous system. When it contracts, it pulls the hair follicle upright, causing the hair to stand up and producing goosebumps. This piloerection is a reflex we experience in cold or fear and it serves mainly to create a layer of air for insulation and to make the hair appear larger in animals.

This muscle doesn’t nourish hair follicles—that’s provided by blood supply to the follicle and the hair papilla. It doesn’t secrete sebum—that’s the job of the sebaceous glands. It also doesn’t control hair pigment—that pigment comes from melanocytes in the hair matrix. So the function being tested is the contraction of the arrector pili leading to hair standing upright, i.e., goosebumps.