Intuitively, pain and itching are very different. However, there are many similarities in their physiological basis: both pain and itching are conducted through Aδ and C fibers; These two fibers project to the spinal dorsal root, and many neurons in the spinal dorsal root respond to pain and itchy stimuli. There is also a lot of overlap in the brain regions activated by pain and itching. Some patients with congenital painless can't feel itchy either. There seems to be a lot of connections between the neural pathways of pain and itching, so some scholars suggest that pain receptors include itch receptors, that is, itching is a kind of pain in the general sense. What is the difference between pain and itching in peripheral receptors, so is it included or not? First, we can consider whether there is a similar relationship between stimuli that can cause pain and itching. It is not difficult to find that there are great differences between these stimuli, such as acupuncture or heavy blows, capsaicin can cause pain, and histamine can make people feel itchy. Different stimuli will activate different receptor proteins. For example, mechanical stimulation will activate mechanical receptors, and chemicals such as capsaicin and histamine have their own receptors.