A biogenic amine and hormone belonging to catecholamines that also functions as a neurotransmitter. It is secreted by the adrenal medulla and by neurons of the sympathetic nervous system into the bloodstream in response to anxiety, fear and stress, and thus is the most potent stimulant of the sympathetic nervous system. When secreted, it leads to an accelerated heart rate, closure of the sphincter with a consequent retention of urine, deeper respiration, dilation of the pupils, diversion of blood from the intestinal smooth muscles to the skeletal muscles, an increase in blood pressure, and the release of sugar from stores in the liver. It is thus part of the ‘flight response’. The hormone was first identified in 1895 by Napoleon Cybulski (1854-1919), with its rediscovery by Jokichi Takamine (1854-1922) in 1901 who called it adrenaline, and synthesized artificially for the first time in 1904 by Friedrich Stolz (1860-1936). Adrenaline is the UK designation after the adoption of the name by Henry Hallett Dale (1875-1968) for the US term epinephrine.
See Adrenal glands, Adrenal medulla, Autonomic nervous system, Catecholamines, Dopamine, Hormones, Mesencephalic reticular activating system, Neurotransmitters, Norepinephrine (or noradrenaline), Stress (or adrenal) hormones, Striated ((or striped or voluntary) muscle, Sympathetic nervous system (SNS)