<prompt> Source of norepinephrine is?PhenylalanineAlanineTyrosineTryptophan  <response>: Tyrosine REF: Lehninger Principles of Biochemistry 4th Edition page 440, 678, and 859 Tyrosine gives rise to a family of catecholamines that includes dopamine, norepinephrine, and epinephrine Norepinephrine is synthesized by a series of enzymatic steps in the adrenal medulla and postganglionic neurons of the sympathetic nervous system from the amino acid tyrosine 