Sympathetic excitation is manifested in the following ways: first, the effect on the circulatory system. Sympathetic excitation, in general, constricts the peripheral arteries, and the treatment of peripheral vascular disorders and the implementation of sympathectomy is based on this; secondly, the action on the digestive system. Sympathetic nerve action on the gastrointestinal tract is mainly inhibition to slow down peristalsis, but when gastrointestinal tension is too low, or inactive, sympathetic impulses, then can be raised and excited; third, the role of the respiratory system. Sympathetic excitation on the small bronchi mainly inhibits the activity of its smooth muscle, thus enlarging the small bronchi and making the air go in and out smoothly; fourth, the effect on the urinary system, sympathetic excitation can make the bladder wall relax and the internal sphincter contract, thus preventing the discharge of urine.