The system of the body that includes the skin, hair, nails, and glands is the:

The integumentary system is the body system that includes the skin, hair, nails, and associated glands (oil and sweat glands). It forms the body's external covering and protective barrier. Because cosmetology services focus on the skin, hair, and nails, the integumentary system is especially relevant to the profession. Other body systems — skeletal, muscular, nervous, circulatory — are studied at a basic level for the parts relevant to head, face, neck, and hand services. Knowing the integumentary system by name is common exam content.