For instance today I removed a mole with excision (cutting it off) at the doctors office with local anaesthesia of course. It has been hours since the procedure and the anaesthesia is long gone, yet I’ve felt barely any pain while literally still having an open wound (no stitches) on my back. I’ve noticed this with other types of pains as well, breaking my wrist, getting bruises from falling and superficial cuts and wounds. The only time I’ve had pain for days was after an actual big surgery. Why is pain often so short lived?
In: Biology
During acute pain, the nerves in your spinal cord release two neurotransmitters to send the pain signal to the brain: glutamate and substance P. However, if the pain persists, your body may start to produce endorphins. These act to inhibit the release of substance P by binding to opioid receptors. Thus mainly glutamate is released, and your brain perceives this as dull pain rather than sharp acute pain. This is same mechanism as drugs like morphine.
The evolutionary reason is presumably that persistent acute pain can distract you from other important things. So when it seems that there is no immediate end to the pain, the body says “OK, well I’ll dial it down and let you get on with getting on with some basic functions”.
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