why is temperature pain delayed but needle pain is immediate?

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If you spill hot water on your hand it takes a second to register as painful but a needle prick is immediately painful. Why?

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It takes (a short amount of) time for the heat in the water to transfer to and heat up the skin on your hand to the point of registering pain, as opposed to the physical contact of the needle penetrating tissue being much more immediate.

Pain is felt when nerves are stimulated. Needles are jammed through multiple layers of skin, quickly (if you are being treated kindly). The pain from a burn will register once the damage is deep enough to hit nerves. It depends on how hot, and how deep, the burn goes. I can tell you that I immediately feel the pain of a burn when my forearm bumps my 500 degree (Fahrenheit) oven.

So you know how if you put a pot of boiling water on a hot stove, it doesn’t immediately boil? It needs time to heat up. It’s the same with spilling hot water on your hand. The temperature sensing cells in your skin need time to actually heat up enough that they can detect that you’re being burned.