They respond to various stimuli, including contact, heat, and cold. In humans, whorls on the fingers show where the epidermis falls between rows of papillae, making the patterns used in fingerprinting. The skin provides a barrier against invasion by outside organisms and protects underlying tissues and organs from abrasion and other injury, and its pigments shield the body from the dangerous ultraviolet rays in sunlight. It also waterproofs the body, preventing excessive loss or gain of bodily moisture. The skin is lubricated by its own oil glands, which keep both the outside layer of the epidermis and the hair from drying to brittleness.
Human skin has remarkable self-healing properties, particularly when only the epidermis is damaged.
Even when the injury damages the dermis, healing may still be complete if the wounded area occurs in a part of the body with a rich blood supply. Deeper wounds, penetrating to the underlying tissue, heal by scar formation. The Columbia Encyclopedia, Sixth Edition.