The document discusses the integumentary system. It consists of the skin, hair, nails, and glands. The integumentary system protects the body from external threats, retains body fluids, regulates temperature, and helps dispose of waste. It works as a barrier against pathogens and physical trauma. The skin and other parts work with other body systems like the digestive, circulatory, and nervous systems to maintain cell and organ function, manage calcium intake, block substances from the bloodstream, and sense touch.