The integumentary system, formed by the skin, hair, nails, and associated glands, enwraps the body. It is the most visible organ system and one of the most complex. Diverse in both form and function—from delicate eyelashes to the thick skin of the soles—the integumentary system protects the body from the outside world and its many harmful substances. It utilizes the Sun's rays while at the same time shielding the body from their damaging effects. In addition, the system helps to regulate body temperature, serves as a minor excretory organ, and makes the inner body aware of its outer environment through sensory receptors.