Final answer:
The integument refers to the outer protective layer of an organism, which in humans includes the skin, hair, and nails, all of which are part of the integumentary system contributing to protection and homeostasis.
Step-by-step explanation:
The term integument refers to an organism's outer protective layer, which in humans includes the skin, hair, and nails. These elements together constitute the integumentary system. This system's primary functions are to provide a protective covering for the body, sense environmental changes, and assist in maintaining homeostasis.
The skin, being the body's largest organ, consists of two main layers: the epidermis and the dermis, which have specialized functions including the synthesis of vitamin D and protection against various threats. Furthermore, both hair and nails contain keratin, a strong protein that adds durability and assists in protection.