Why fingers shrivel in the water?

On the fingers and palms of the hands, as well as the toes and soles of the feet, is a type of skin known as glabrous skin. This skin is characterized by not having hair or hair and by having a different response to water than the rest of the skin, wrinkling if it gets wet enough. If the hand is kept submerged, the fingers begin to wrinkle after about 5 minutes.

This reaction occurs in the epidermis, the outermost skin layer. The cells of the epidermis contain high amounts of keratin, a protein with a fibrous structure very rich in sulfur. Dead layers of these cells are deposited on the epidermis and form the stratum corneumwhich is responsible for the resistance of the skin and prevents its dehydration.

The stratum corneum is capable of absorb water and swell after remaining submerged in water for a while, while living keratin cells from deeper layers do not. As the stratum corneum swells, it occupies more and more surface, each time it has a larger area, but at the same time it remains attached to the lower layers. To compensate for the surface difference between both layers, the stratum corneum folds and wrinkles.

This effect could occur in any part of the body, but it occurs mainly in the hands and feet because in these areas subjected to continuous use, the stratum corneum is usually much thicker. These wrinkles due to hydration of the stratum corneum are reversible and the skin returns to its normal state when it dries.

Various mechanisms have been proposed by which the skin wrinkles when immersed in water. The main one would be the absorption of water by osmosis. It is also believed that the constriction of superficial blood vessels, specifically those that irrigate the glomus apparatus, structures of the dermis involved in temperature regulation; by reducing the blood supply, the glomus apparatus would reduce its volume and favor the appearance of wrinkles in the upper layers.

The mechanism of vasoconstriction involves the nervous system and it can be verified how patients with loss of nerve function in the hands do not present wrinkles in the fingers after immersing them in water or they appear weak. If nerve function recovers, wrinkles reappear.

possible function

There is a theory that the ability of the skin on the fingers to wrinkle is a characteristics acquired through evolution. The wrinkles in the fingers would act as channels for the expulsion of water helping to handle wet objects or to have greater grip when walking on wet surfaces, similar to the function of car tire treads.

This evolutionary theory, described by mark changiz in 2011, it could not be corroborated and there are studies on the ability to manipulate objects with wrinkled fingers with contradictory conclusions.

Go up