Why does it sting when water touches a recent wound?



Or, why does it sting only initially when a wound comes in contact with water and goes away even if contact with water is maintained?

In: Biology

You cut yourself. You feel pain because your receptors say “ouch, you’re injured.” You pour water on it and your nerves say “ah more foreign stuff!” and thus send a pain signal again. Also if you have a cut you could be making the broken skin or tissue move, pissing your pain receptors off more. Your pain receptors are very sensitive after injury because broken cells release chemicals that lower your pain threshold.
Eventually your body kind of connects the dots and lets the water happen so long as it’s not too powerful (so it doesn’t flap the skin or whatever).

After some time, your immune cells clear away the chemicals and broken cells, increasing your pain threshold.

That’s the general gist.

Edit: added that last “after some time…” part.