Endorphins

Endorphins are endogenous opioid peptides produced in the CNS. The word endorphin comes from a word creation of "endogenous" and "morphine". Similar to narcotics, endorphins give good feelings. Runners feel the effect of these hormones during the so-called "Runners High".

Endorphins are transmitters that are used, among other things, to control pain. Like opiates, they bind morphine, heroin and others to various types of opiate receptors located in the membranes of pain-mediating neurons. The transmission of pain impulses in the spinal cord can be modulated and suppressed via these opoid receptors.

https://de.wikipedia.org/wiki/Endorphine _{(Wikipedia CC-by-sa-3.0)}