Adrenal gland
In humans, a gland on the anterior aspect of the superior portion of both kidneys, each weighing 4 grams. An adrenal gland consists of two main parts:
- The adrenal medulla is innervated by the sympathetic nervous system and takes up the core 20% of the adrenal gland. It secretes two hormones (both catecholamines) into the blood: epinephrine and norepinephrine. The adrenal medulla produces about 80% epinephrine and 20% norepinephrine. Epinephrine and norepinephrine are also known as adrenaline and noradrenaline (respectively), but this trend seems to be coming to an end as the international community (especially Europe) pushes towards using non-propriety naming conventions (Adrenaline is a trade name). Britain seems to be opposed to this, as they percieve "epinephrine" as an Americanization of the British-approved name, "adrenaline."
- The adrenal cortex is activated by adrenocorticotrophic hormone sent out from the anterior lobe of the pituitary gland. The adrenal cortex takes up the remaining 80% of the adrenal gland. It secretes hormones, called corticosteroids - glucocorticoids, mineralocorticoids and androgens, which are produced from the steroid cholesterol. The androgens play a minor role as a sexual hormone that regulates some traits of masculinity (much like testosterone). The glucocorticoids play a part in the regulation of glucose levels in the blood, protein metabolism, and fat metabolism. The mineralocorticoids help regulate the extracellular concentrations of electrolytes (such as potassium and sodium). Although the adrenal cortex has been found to produce over 30 steroids of the aforementioned types, the only two steroids that have a major bearing on the normal function of the endocrine system are aldosterone (the major mineralocorticoid), and cortisol (the main glucocorticoid).
References:
- Textbook of Medical Physiology, 10 ed., Guyton and Hall.
- Paramedic Emergency Care, 3 ed., Bledsoe, Porter, and Shade.
- What's in a name?, The Pharmaceutical Journal Vol 264 No 7087 p388 (url: http://www.pharmj.com/Editorial/20000311/comment/name.html).
- Adrenalin - epinephrine, Stein Lyftingsmo, e-drug mailing list, (url: http://old.healthnet.org/programs/e-drug-hma/e-drug.200002/msg00060.html).