How do specialized nociceptor neurons detect tissue damage

Discuss the physiological mechanisms underlying the sensation of pain, including nociception, transmission, modulation, and perception. How do specialized nociceptor neurons detect tissue damage and transmit pain signals to the spinal cord and brain via the ascending pain pathways? Furthermore, how do endogenous pain-modulating systems, such as the descending pain inhibition pathway and the release of neurotransmitters like endorphins and serotonin, regulate pain sensitivity and contribute to analgesia and pain relief?