Answer to Question #53086 in Other Biology for abhi
why does the skin of your finger shrink when someone washes clothes for a long time?
The most widespread explanation is that skin readily absorbs water and thus swells. The human skin is made of two layers: epidermis (the outer layer that everyone could see) and dermis (the layer underneath that contains blood vessels). Epidermis consists of dead cells enriched with keratin. Keratin is an insoluble protein but it is capable to swell in water. After absorbing water, the outer layer expands. As it is tightly connected with dermis, epidermis compensates its increased square and swells.
However, this hypothesis does not explain why other skin of human body does not wrinkle after bath or swimming. Also, the skin on the fingers does not wrinkle at all when the nerve endings are damaged either after trauma or as complication after diabetes.
Thus, another explanation exists. When fingers have been under water for a long time, the nervous system sens a signal to the blood vessels in the dermis to constrict. The volume of the dermis reduces, as a result, the epidermis forms wrinkles.