A group of hormones that act as neurotransmitters, which are mainly manufactured by the chromatin cells (the secretory organelles) of the medulla of the adrenal glands and from the postganglionic fibbers of the sympathetic nervous system. The most abundant catecholamines are three closely related chemical messengers:epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine, all of which are made from amino acid tyrosine, and thus are referred to as biologically active amines or monoamines. They are involved in preparing the body for the ‘fight-or-flight’ response. When released, the heart beats stronger and faster, blood pressure rises, more blood flows to the brain and muscles, the liver releases stores of energy as a sugar (glucose) that the body can readily use, the rate of breathing increases and airways widen, while digestive activity slows down. The result of these reactions is to direct more oxygen and fuel to the organs most active in responding to stress, mainly the brain, heart, and striated muscles.
See Adrenal cortex, Adrenal glands, Adrenal medulla, Autonomic nervous system (ANS), Cardiac muscle, Dopamine, Epinephrine (or adrenaline), Hormones, Locus coeruleus (or ceruleus), Neurotransmitters, Noradrenergic neurotransmiter system, Norepinephrine (or noradrenaline), Striated ((or striped or voluntary) muscle, Sympathetic nervous system (SNS), Tyrosine kinase receptor/pathway