Which of the following is a function of the integumentary system?

• A. Protection
• B. Digestion
• C. Oxygen transport
• D. Hormone production

Answer: (A)

Protecting the body's interior and preventing water loss is the key function the integumentary system provides. The skin forms a tough, waterproof barrier with the epidermis made of keratin-filled cells that resist mechanical injury and limit water loss. Melanin helps shield tissues from UV damage, and immune cells in the skin contribute to defense against pathogens. Together, these features keep microbes out and dehydration at bay, which is the core protective role of this system.

Digestion belongs to the digestive system, oxygen transport to the circulatory system, and hormone production to endocrine processes. The skin does participate in vitamin D synthesis under sunlight, which influences calcium metabolism, but that is not its primary function and doesn’t replace the protective barrier it provides.