The biggest difference between the two is that the nervous system uses electrical impulses to send signals through neurones, whereas the hormonal system uses chemical messengers transported into blood plasma to target cells. Transmission by the nervous system is short-lived but quick, whereas transmission by the hormonal system is long-lasting but takes much longer. This means that communication is faster when using the nervous system. In the nervous system, responses are localised - whereas in the hormonal system, they are widespread. Responses are often permanent in the hormonal system, but temporary and reversible in the nervous system.