The integumentary system is composed of the organs (like the skin) forming the outmost layer of the body, being a physical barrier that protects and maintains the internal environment. The main difference between frog and human integumentary systems is that in frogs it also serves as a respiratory organ, as in humans it does not. The frogs also secretes mucus and poison (for protection) through the skin, but humans secretes only sweat and sebum. The skin of a frog can absorb water as well, as the human's integumentary system is water proof. The frogs integumentary system is composed only of its skin, but in humans it also includes hair, nails, glands and sensory nerves.