Skin is the soft outer covering of vertebrates. Other animal coverings such as the arthropod exoskeleton have different developmental origin, structure and chemical composition. The adjective cutaneous means "of the skin" (from Latin cutis, skin). In mammals, the skin is the largest organ of the integumentary system made up of multiple layers of ectodermal tissue, and guards the underlying muscles, bones, ligaments and internal organs. Skin of a different nature exists in amphibians, reptiles, and birds. All mammals have some hair on their skin, even marine mammals which appear to be hairless. The skin is one of the most important parts of the body because it interfaces with the environment and is the first line of defense from external factors. For example, the skin plays a key role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, and the production of vitamin D folates. Severely damaged skin may heal by forming scar tissue. This is sometimes discoloured and depigmented. The thickness of skin also varies from location to location on an organism. In humans for example, the skin located under the eyes and around the eyelids is the thinnest skin in the body at 0.5 mm thick, and is one of the first areas to show signs of aging such as "crows feet" and wrinkles. The skin on the palms and the soles of the feet is 4 mm thick and the thickest skin in the body.
Fur is dense hair. Primarily, fur augments the insulation the skin provides but can also serve as a secondary sexual characteristic or as camouflage. On some animals, the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier to passage of chemicals and is often subject to osmosis. For example, a frog sitting in an anesthetic solution could quickly go to sleep.
Other articles related to "skin":
... Look up skin in Wiktionary, the free dictionary. ...
... of dead tissue that is cast off from the surface of the skin, particularly after a burn injury, but also seen in gangrene, ulcer, fungal infections, necrotizing spider bite wounds, and exposure to ... if a skin graft is to be conducted) ... extracts, were traditionally used in herbal medicine as topical treatments for localised skin cancers and can be effective in some cases, but often cause scarring and can potentially cause ...
... In computing, a skin is a custom graphical appearance achieved by the use of a graphical user interface (GUI) that can be applied to specific software and websites to ... A skin may be associated with themes ... Software that is capable of having a skin applied is referred to as being skinnable, and the process of writing or applying such a skin is known as skinning ...
... are contracting are causing a "bunching" of the skin surrounding the hairs, which results in the "bumps" in goosebumps ... of preserving its own heat by causing the hairs on the skin to stand up, thus reducing heat loss ... As the perspiration accumulates on the skin, it naturally evaporates ...
... Since the skin reaction is an allergic one, people may develop progressively stronger reactions after repeated exposures, or show no immune response on their first exposure, but show sensitivity on following ... a trace of urushiol (two micrograms or less than one ten-millionth of an ounce) on the skin to initiate an allergic reaction (Epstein et al ... (1–2 mm) clear fluid-filled blisters on the skin ...
Famous quotes containing the word skin:
“What, is the jay more precious than the lark
Because his feathers are more beautiful?
Or is the adder better than the eel
Because his painted skin contents the eye?”
—William Shakespeare (15641616)
“Her skin was white as leprosy,
The nightmare Life-in-Death was she,
Who thicks mans blood with cold.”
—Samuel Taylor Coleridge (17721834)
“The bottom line on bonding with multiples seems to be that if you see bonding as a static eventa moment in time at which you must have eye contact and skin contact simultaneously with two or more infantsyou may indeed be in trouble.”
—Pamela Patrick Novotny (20th century)