Adrenal gland
A number of endocrine diseases involve dysfunctions of the adrenal gland. Overproduction of cortisol leads to Cushing's syndrome, whereas insufficient production is associated with Addison's disease. Congenital adrenal hyperplasia is a genetic disease produced by dysregulation of endocrine control mechanisms. A variety of tumors can arise from adrenal tissue and are commonly found in medical imaging when searching for other diseases.
The adrenal glands are located on both sides of the body in the retroperitoneum, above and slightly medial to the kidneys. In humans, the right adrenal gland is pyramidal in shape, whereas the left is semilunar or crescent shaped and somewhat larger. The adrenal glands measure approximately 3 cm in width, 5.0 cm in length, and up to 1.0 cm in thickness. Their combined weight in an adult human ranges from 7 to 10 grams. The glands are yellowish in colour.
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.