• The adrenal medulla constitutes about 20% of the adrenal gland.
• It secretes catecholamines: epinephrine, norepinephrine, and dopamine.
• The secretion from the adrenal medulla is composed of 20% norepinephrine and 80% epinephrine.
• The adrenal medulla is viewed as a modified sympathetic ganglion, where postganglionic neurons have lost their axons and transitioned into secretory cells.
• Catecholamines are derived from the amino acid tyrosine, which is transported and then concentrated by the adrenal medullary cells.
• Adrenal medullary cells contain the enzyme phenyl ethanol-amine N-methyl transferase (PNMT) which facilitates the conversion of norepinephrine into epinephrine.
• The activity of adrenal medullary PNMT is stimulated by glucocorticoids.

As for the metabolic action of epinephrine:

• In the liver: Epinephrine enhances the activity of liver and muscle phosphorylase, promoting glycogenolysis. This action increases glucose output by the liver.
• In skeletal muscle: Epinephrine encourages glycogenolysis. However, since muscle lacks glucose-6 phosphatase, glucose cannot be released by skeletal muscle. Instead, it must be metabolized at least to lactate before being released into the circulation.
• In adipose tissue: Epinephrine increases lipolysis by raising the activity of hormone-sensitive lipase. Glycerol, which is produced from TG breakdown, is a minor substrate for gluconeogenesis.

Pheochromocytoma.

• Sketchy.
• Osmosis.