Adrenal cortex

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Adrenal cortex

Layers of cortex.
Latin	cortex glandulae suprarenalis
Gray's	subject #277 1278
Dorlands/Elsevier	c_57/12261690

Cortical part part of the adrenal glad (on the pointer).

Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis.

1 Layers
2 Steps of hormone synthesis
3 Production
- 3.1 Androgens
4 Mnemonics
5 Pathology
6 See also
7 External links

[edit] Layers

The cortex can be divided into three distinct layers of tissue based on their organization.

Layer	Name	Primary product
Most superficial cortical layer	zona glomerulosa	mineralocorticoids (eg, aldosterone)
Middle cortical layer	zona fasciculata	glucocorticoids (eg, cortisol)
Deepest cortical layer	zona reticularis	weak androgens (eg, dehydroepiandrosterone)

[edit] Steps of hormone synthesis

All adrenocortical hormones are synthesised from cholesterol.

Cholesterol is transported into the inner mitochondrial membrane by steroidogenic acute regulatory protein (STAR), where it is converted into pregnenolone by the enzyme CYP11A1. Accordingly, production of hormones in all three layers of the adrenal cortex is limited by the transportation of cholesterol into the mitochondria and by its conversion into pregnenolone.

Pregnenolone can be either dehydrogenated to progesterone or hydroxylated to 17-alpha-hydroxypregnenolone.

The steps up to this point occur in many steroid-producing tissues. Subsequent steps, however, only occur in the adrenal cortex:

Progesterone ->	(hydroxylation at C21)->	Deoxycorticosterone ->(two further hydroxylations)->	Aldosterone
Progesterone ->	(hydroxylation at C17)->	17-alpha-hydroxyprogesterone ->(hydroxylation)-> Deoxycortisol ->(hydroxylation)->	Cortisol

[edit] Production

The primary glucocorticoid released by the adrenal gland is cortisol. Upon binding to its target, cortisol enhances metabolism in several ways:

stimulating the release of amino acids from the body
stimulating lipolysis, the breakdown of fat
stimulating gluconeogenesis, the production of glucose from newly-released amino acids and lipids
conserving glucose by inhibiting uptake into muscle and fat cells

[edit] Androgens

In addition to glucocorticoid production, the fasciculata is a secondary source of androgens such as testosterone, dihydrotestosterone (DHT), androstenedione, and dehydroepiandrosterone (DHEA). These enhance muscle mass, stimulate cell growth, and aid in the development of the secondary sex characteristics.

[edit] Mnemonics

The layers of the cortex can be remembered with the mnemonic GFR: G - glomerulosa, F - fasciculata, R - reticularis.

Another mnemonic that is used is Go Find Rex, Make Good Sex: G - glomerulosa, F - fasciculata, R - reticularis, M - mineralcorticoids, G - glucocorticoids, S - sex hormones. (This mnemonic simplifies the relationship between the locations of production of glucocorticoids and sex hormones.)