Which system protects the body as a whole from the external environment and forms the external body covering?

• A. Integumentary system
• B. Digestive system
• C. Nervous system
• D. Endocrine system

Answer: (A)

The integumentary system serves as the body's external barrier and covering. It includes the skin and its derivatives like hair, nails, and glands, and provides a physical shield against environmental hazards, limits water loss, and helps regulate temperature. The epidermis, as the outermost layer, is key to this barrier function, while nerves and glands in the skin contribute to sensation and protection. The other systems have different primary roles—digestion processes food and nutrients, the nervous system coordinates rapid responses, and the endocrine system regulates body functions with hormones—so they don’t form the external covering or protection the skin provides.