Adrenal gland
The adrenal glands are named for their location relative to the kidneys. The term "adrenal" comes from "ad-" (Latin, "near") and "renes" (Latin, "kidney"). Similarly, "suprarenal", as termed by Jean Riolan the Younger in 1629, is derived from the Latin "supra" () and "renes" (). The suprarenal nature of the glands was not truly accepted until the 19th century, as anatomists clarified the ductless nature of the glands and their likely secretory role – prior to this, there was some debate as to whether the glands were indeed suprarenal or part of the kidney.
Adrenaline
Epinephrine is synthesized in the medulla of the adrenal gland in an enzymatic pathway that converts the amino acid tyrosine into a series of intermediates and, ultimately, epinephrine. Tyrosine is first oxidized to -DOPA by Tyrosine hydroxylase, this is the rate-limiting step. Then it is subsequently decarboxylated to give dopamine by DOPA decarboxilase (Aromatic L-amino acid decarboxylase). Dopamine is then converted to norepinephrine by dopamine beta-hydroxylase or dopmanine beta-monooxygenase which utilizes ascorbic acid (Vitamin C and copper. The final step in epinephrine biosynthesis is the methylation of the primary amine of norepinephrine. This reaction is catalyzed by the enzyme phenylethanolamine "N"-methyltransferase (PNMT) which utilizes "S"-adenosyl methionine (SAMe) as the methyl donor. While PNMT is found primarily in the cytosol of the endocrine cells of the adrenal medulla (also known as chromaffin cells), it has been detected at low levels in both the heart and brain.
The major physiologic triggers of adrenaline release center upon stresses, such as physical threat, excitement, noise, bright lights, and high or low ambient temperature. All of these stimuli are processed in the central nervous system.