When you have a small chunk of skin removed, say you cut your fingertip off, how does the body know how much skin to replace to get it looking like it did before the injury?

Question

It regrows to the exact size it was, no extra skin no less skin. Unless of course it’s a serious injury but I’m talking minor skin removal. Obviously gunshot wounds, flesh eating bacteria and animal bites don’t do this because of scar tissue I assume but even with them it’s remarkable how close it comes to filling in the area. How does the body know when to stop growing the new tissue to fill it in and how come with these deeper wounds the body has a harder time figuring it out?

In: Biology

Answer 1

Basically every cell in your body has an internal set of instructions to follow. For skin, one of the primary jobs is to either grow or not. So each skin cell is sitting there and constantly going over a checklist of if it’s time to divide or not. “Ok, has it been a while since the last time I divided? Yup. Am I big enough? Yup. Is there room for another cell next to me? Nope…dang. Start over.” So, if you have a wound your skin cells recognize that there’s not skin cells next to them and start dividing to fill the gap. Once they’re surrounded by skin cells they stop.

A “fun” fact is that this is pretty much what cancer comes from. Basically something (radiation, chemicals, copy error, dumb luck) damages the “check list”. Most of the time when the list is damaged it will be unintelligible and the cell will just sit idle until it dies, but once in awhile the list is damaged in such a way that it most of the conditions that would trigger a stop get ignored. “Ok, has it be awhile since I last divided? Who cares. Am I big enough to divide? Your mom thought I was big enough. Is there room next to me? Fuck it, it’s go time!” So the cell divides like crazy making a bunch of cells that divide like crazy.

edit: welp, thanks for all the replies and metals, but now I’m gonna be late for work. Thanks jerks 😉 ! Also, a couple of people have said I’m wrong which honestly doesn’t surprise me much. Don’t, like, make any serious medical decisions based on some rando on reddit in a sub based on explaining things as if to children, k?