Eli5 how do you get frostbite and how long do your fingers or toes have to be exposed to the cold before you will actually get it?

Question

I am very curious, I have seen some images where people’s fingers just rot and I don’t understand how this process works, like can’t you just put them under the warm water and save your hands or feet? And how to notice the frostbite thing progressing in your fingers? It scares the poop out of me that I might get it someday unconsciously..

In: 2

Answer 1

Water expands when it freezes, right? Well your cells are delicate little pouches, and they’re filled mostly with water. If a body part gets cold enough, the water inside the cells can freeze. If that happens, the expanding ice crystal rips the cell apart. After that happens, warm water or any other thawing method doesn’t help because the cells are already ruptured and spilling their contents everywhere.

For an experiment you could actually do with a 5 year old, freeze a piece of fruit like an apple slice until it’s solid, then thaw it again. No matter how carefully you thaw it, it’s going to be complete mush afterwards because the cells all ripped open when it froze.