>> The medulla of the adrenal gland secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) to help the body respond to stress. The regulation of these hormones is controlled by the neurons of the hypothalamus, which send impulses to the adrenal medulla in response to stress. For example, stressful situations result in the fight or flight response by increasing the levels of adrenaline and noradrenaline in the blood. The release of these two hormones results in an increase in heart rate, respiratory rate, and blood glucose levels. Simultaneously, cardiac and skeletal vessels dilate in order to increase the amount of oxygen, blood, and glucose. Other regions of the body, such as vessels of the digestive tract, constrict because digestion becomes of secondary importance when the body is trying to flee a stressful situation. Thus, the nervous system controls muscle movement by controlling the release of hormones.