What is the primary function of the integumentary system?

The primary function of the integumentary system is to provide support and protection for the body. This system includes the skin, hair, nails, and associated glands, all of which play pivotal roles in safeguarding the body from environmental hazards, pathogens, and physical injury. The skin serves as the first line of defense, acting as a barrier to bacteria and other harmful substances while also protecting against UV radiation and physical trauma. Additionally, the integumentary system helps to regulate body temperature and facilitates sensory perception, enhancing overall body homeostasis.

While the other options address important physiological functions—such as hormonal balance being primarily managed by the endocrine system, blood flow regulation mostly handled by the circulatory system, and hydration connected to both internal and external mechanisms—these are not the central roles of the integumentary system. Thus, the correctness of the primary function emphasizes its role in protecting and supporting the body structure.