Why do my fingers go wrinkly in the bath?

25 July 2010

Question

Why do my fingers go wrinkly in the bath?

Answer

Chris: - The reason that you get wrinkly fingers in the bath is because the skin on your fingers and hands and toes is quite thick, and it's there to protect you. You have a slight thickening of the skin because we tend to rub our fingers against things more often than we rub other bits of our body with things and the skin becomes thicker there to compensate. The top layers of that thickened skin are flat, dried-out, dead cells. In fact, they're falling off of you all the time. If you could total up the number of cells that you're losing, it's about 40,000 skin cells a minute that fall off of you. If you added them all up, that's 1 Ã?,½ stone in dead skin over a lifetime. Now that dead skin on your fingers which is still attached, despite being a flattened thick layer, is nonetheless slightly penetrable by water, and water can get into that layer, and it makes the thin flattened cells swell up a bit. And in the same way that if you make railway lines very, very warm, they can buckle and bend which is why you have to leave a gap between them, the skin cells to the same thing. They swell up, they press into each other, and as a result, they push each other out of the way, and they get thrown up into all these ridges and folds because the cells are bigger, because they've got water in them. After you get out of the bath or the sea, or the swimming pool, and you dry out again, that extra moisture that's got into the cells comes back out, the cells flatten out again, and they go back to their normal shape, and that's why you go wrinkly in the bath.

----UPDATE-----

In 2013 UK scientists discovered that fingers go wrinkly in water to improve our grip on wet or submerged object. They also showed that it is in fact constricting blood vessels, not osmosis, that drives this change.

http://www.karger.com/Article/FullText/328223

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