Epinephrine (also known as
adrenaline or
adrenalin) is a
hormone and a
neurotransmitter. Epinephrine has many functions in the body, regulating
heart rate,
blood vessel and air passage diameters, and metabolic shifts; epinephrine release is a crucial component of the
fight-or-flight response of the
sympathetic nervous system. In chemical terms, epinephrine is one of a group of
monoamines called the
catecholamines. It is produced in some
neurons of the central nervous system, and in the
chromaffin cells of the
adrenal medulla from the
amino acids
phenylalanine and
tyrosine.