Which of the following is not a function of the skin?

• A. Regulation of temperature
• B. Excretion of sweat
• C. Protection from infection
• D. Synthesis of hormones

Answer: (D)

The skin has multiple practical roles in maintaining body balance and defending the body. It helps regulate temperature by producing sweat to cool the body and by adjusting blood flow to the skin to conserve or lose heat. It also serves as a barrier, protecting against infection through its physical barrier, skin oils, and immune components like antimicrobial peptides. It also participates in excretion to some extent via sweat.

However, hormones are chemicals produced by endocrine glands and released into the bloodstream to act on distant targets. The skin does not function as an endocrine gland and does not actively synthesize hormones for systemic release. It does synthesize vitamin D when exposed to sunlight, but that is a precursor to a hormone after further activation in the liver and kidneys, not direct hormone production by the skin itself.

So, the statement that the skin does not function in hormone synthesis is correct.