The six functions of skin are protection, absorption, secretion, excretion, sensation, and:

• A. Tanning
• B. Penetration
• C. Heat regulation
• D. Reducing muscle tension

Answer: (C)

Heat regulation is a function of the skin. Beyond serving as a protective barrier, the skin helps keep body temperature in balance. Sweat glands release sweat onto the surface, and as it evaporates, it cools the body. Blood vessels in the skin can dilate to release more heat or constrict to conserve heat, adjusting heat loss as needed. This temperature-control role sits alongside protection, absorption, secretion, excretion, and sensation.

Tanning is a pigmentary change in response to UV exposure, not a fundamental skin function. Penetration isn’t a separate listed function—absorption covers substances entering the skin, while penetration would be a more specific idea of how deeply something passes through. Reducing muscle tension isn’t related to what the skin does.