Epinephrine and norepinephrine are the hormones secreted by the adrenal medulla and are also called adrenaline and noradrenaline, respectively. During stress conditions, the hypothalamus stimulates the preganglionic neurons of sympathetic division.
These preganglionic neurons stimulate the chromaffin cells to secrete epinephrine and norepinephrine to prepare the body for fight or flight response. The increased level of epinephrine and norepinephrine hormones in the blood is called “surge of adrenaline”
When blood is rich in carbon dioxide it leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs. (All of which have to do with the circulatory system)
