In the integumentary system, contraction of the piloerector (arrector pili) muscle produces which visible effect on the skin?

• A. Increased secretion of sebum from sebaceous glands onto the hair
• B. Elevation of the hair shaft, producing "goosebumps" (piloerection)
• C. Dilation of dermal blood vessels to increase heat loss
• D. Initiation of new hair growth by stimulating the hair matrix to divide

Answer: (B)

Verified step by step guidance

1. Understand the role of the piloerector (arrector pili) muscle in the integumentary system. This small muscle is attached to hair follicles in the skin.
2. Recall that when the piloerector muscle contracts, it pulls on the hair follicle, causing the hair shaft to stand upright.
3. Recognize that this action results in the visible effect known as piloerection, commonly referred to as "goosebumps."
4. Note that this contraction does not increase sebum secretion, dilate blood vessels, or initiate new hair growth; these are functions of other structures or processes.
5. Conclude that the contraction of the piloerector muscle produces the elevation of the hair shaft, which creates the characteristic appearance of goosebumps on the skin.