the brain is a part of the central nervous system
central_nervous_system is internal_body_part. nervous_system is body_part. peripheral_nervous_system is brain. central_nervous_system is body_part. central_nervous_system is system. central_nervous_system is not system. central_nervous_system is not body_part. central_nervous_system is not organ_system. central_nervous_system is not internal_body_part. central_nervous_system is organ_system.