Which type of drugs kill pain by blocking impulses at specific receptor sites of the brain and spinal cord?

The answer is narcotic. It is any of a class of substances that limit the faculties, as opium, morphine, belladonna, and liquor, that in expansive amounts deliver elation, trance, or trance state, that when utilized continually can bring about habituation or enslavement, and that are utilized as a part of medication to alleviate torment, cause sedation, and instigate rest.