how do initial stimuluses into a nerve ending cause increased sensitisation to more stimuli for that nerve?

sometimes nerve signals can travel up the nerve and then travel up another part of the nerve instead of going straight to the spinal cord and this can result in Substance P and CGRP release from the nerve cell which results in mast cell activation, this results in histamine production and that causes more sensitisation of the nerve. basically the whole initiation of stimulus causes this pathway making the nerve even more sensitive

what is antedromic impulse

An antidromic impulse in an axon refers to conduction opposite of the normal (orthodromic) direction. That is, it refers to conduction along the axon away from the axon terminal(s) and towards the soma. eg above the histamine sensitisation pathway as described. this also causes inc redness and itching due to the histamine

The calcitonin gene related peptide (CGRP) and Substance P cause what and when?

when there is a pain signal recognised from the nerve and it doesnt go all the way to the dorsal spinal cord it can come back along a different nerve subdivision and cause CGRP and SP release which cause

mast cell activation

the mast cells then produce histamine which is hyperalgesic. they also increase summation in the dorsal horn which increase sensitiviy

Dorsal horn wind-up is a phenomenon in the spinal cord's dorsal horn, where repetitive stimulation of pain fibers leads to progressively increased pain sensitivity. Essentially, wind-up is a form of central sensitization where, after repeated low-level stimulation (such as repetitive or continuous painful stimuli), neurons in the dorsal horn become more responsive, amplifying the perception of pain.