Adrenal gland
The adrenal gland is a gland in most mammals. It is near the kidneys. Its name tells its position (ad – "near", and renes – "kidneys"). The gland is made up of two types of tissues: the centrally located tissue is called the adrenal medulla and outside this lies the adrenal cortex.
The adrenal glands are known as "suprarenal glands" in humans. In many animals the glands are next to the kidneys, but they are cap-like structures on top of the kidneys in humans.
The adrenal cortex produces three main types of steroid hormones: mineralocorticoids, glucocorticoids, and androgens. Mineralocorticoids (such as aldosterone) help in the regulation of blood pressure and electrolyte balance.
The adrenal gland makes hormones which control stress. It is involved in the production of steroid hormones. Among these hormones are cortisol and adrenaline.
Cortex
The hormones secreted from the cortex region are called adrenocorticosteroids or corticoids. These are the hormones it makes:[1]
- Corticosteroids: all corticosteroids are made from cholesterol.
- Cortisol / cortisone. These two are in a reversible reaction: they can be changed to each other by an enzyme. Cortisol is the active version, cortisone is the inactive version.
- Aldosterone: a hormone which regulates blood pressure.
- Androgens: these are intermediate male sex hormones. They are turned into more active hormones in the testes.
Medulla
The adrenal medulla, in the center of the gland, makes:[1]
- Adrenaline (U.S = Epinephrine) and noradrenaline (U.S. = norepinephrine): they make the fight or flight response in animals.[2][3]
Adrenal Gland Media
Adrenal glands, anterior (left) and posterior (right) surface
Section of human adrenal gland under the microscope, showing its different layers. From the surface to the center: zona glomerulosa, zona fasciculata, zona reticularis, medulla. In the medulla, the central adrenomedullary vein is visible.
Different hormones are produced in different zones of the cortex and medulla of the gland. Light microscopy at magnification × 204.
Characteristic skin hyperpigmentation in Addison's disease
Incidences and prognoses of adrenal tumors.
References
- ↑ 1.0 1.1 Melmed S. et al 2011. Williams textbook of endocrinology. 12th ed, Saunders. ISBN 978-1437703245
- ↑ The actions of adrenaline and noradrenaline are responsible for the fight or flight response, characterised by a quickening of breathing and heart rate, an increase in blood pressure, and constriction of blood vessels in many parts of the body.
- ↑ Gleitman, Henry; Fridlund, Alan J. and Reisberg, Daniel (2004). Psychology (6 ed.). Norton. ISBN 0-393-97767-6.
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