A substance secreted by the medulla of the adrenal gland.Since it has important effects on the activity of the sympathetic nervous system, noradrenalin is known as a “neurohormone.” These effects are of two general types. The secretion helps to mobilize energy in meeting emergencies and stress situations; and it is instrumental in producing intense emotional activity, particularly the expression of anger and hostility. The adrenal gland does not act alone, however, but collaborates with other organs, especially the hypothalamus, the pituitary gland, and the cerebral cortex. The exact relationships among these components are a subject of continuing research. It is hoped that these investigations will not only clarify the physical changes that occur in emotion but also the personality changes that take place in neurosis and psychosis.