This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Physiology
[{'content': 'In case a small stimulus causes more pain, it is called: \nSelect and explain. \nA. Hypersensitivity, B. Causalgia, C. Hyperalgesia, D. Allodynia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: - Increase in sensitivity of pain receptors is called hyperalgesia (mostly due to inflammatory mediators) - Small Noxious stimulus giving exaggerated pain sensation - Causes Excessive sensitivity of pain receptors => primary hyperalgesia Facilitation of sensory transmission => secondary hyperalgesia (mainly due to lesions of spinal cord and thalamus) Hypersensitivity - Undesirable reactions produced by normal immune system - E.g. allergies & autoimmunity Allodynia - Non - noxious stimulus gives pain - E.g. trigeminal neuralgia Causalgia - Burning type of pain caused by crushing, injuries to nerves. (neuropathic pain) Nociceptive pain: - Noxious stimulus leads to corresponding degree of pain', 'role': 'assistant'}]