What does the integumentary system primarily consist of?

The integumentary system primarily consists of skin and its accessory structures. This includes components such as hair, nails, sweat glands, and sebaceous (oil) glands. The skin serves as the body's largest organ, playing a critical role in protecting the body from environmental hazards, regulating temperature, and providing sensory information.

By understanding that the integumentary system encompasses not just the skin but also these accessory structures, one can appreciate its comprehensive role in overall health and homeostasis. Other options like muscles and bones relate to the musculoskeletal system, nerves and blood vessels are part of the nervous and circulatory systems respectively, and hair and nails are indeed accessory structures, but they do not encompass the entirety of the integumentary system. Thus, the choice that best describes the complete composition of the integumentary system is skin and accessory structures.