The integumentary system consists of the skin, hair, nails, glands, and nerves. Its main function is to act as a barrier to protect the body from the outside world and help to maintain homeostasis. Hair! How does your hair help protect your body and maintain homeostasis? All BUT ONE answer applies. A) Hair helps to insulate the body. B) Hair follicles produce necessary vitamin D. C) Hair protects your body from the effects of UV radiation. D) Hair can trap particles and minute organisms and keep them from entering your body.