The curriculum asks for knowledge of 'adrenocortical hormones', which is about as succinct as it gets!
The adrenal cortex lies between the outer capsule and the inner medulla of the adrenal gland
Blood supply to the cortex arises from branches of capsular arteries
There is centripetal blood flow from these arteries, passing through the cortical zones and medulla to the medullary veins
The cortex is divided into three, distinct anatomical zones from outer to inner
Zona glomerulosa: responsible for the production of mineralocorticoids (aldosterone)
Zona fasciculata: responsible for the production of glucocorticoids (cortisol)
Zona reticularis: responsible for the production of sex hormones (DHEA and androstenedione)
There are various acronyms for remembering this, including:
'GFR' i.e. the order of the different zonae from outer to inner
'Salt, sugar, sex - the deeper you go the sweeter it gets!' i.e. to remember the order of hormone production by the zones
Embryology
Adrenal hormones are vital for intra-uterine homeostasis and growth/maturation of organ systems
The foetal adrenal gland contains a large 'foetal zone' that produces DHEA-S and (less) cortisol
There is also a definitive (glomerulosa) and transitional (fasciculata) zone that later develop into adult structures
There is no foetal adrenal medulla or zona reticularis; these develop over 1.5yrs and 3-8yrs post-natally respectively
All steroids derive from cholesterol, which is transported into adrenal cells as LDL/HDL's
It is transported within adrenocortical cells to the mitochondria, where its side-chains are removed by the enzyme cholesterol desmolase
This is the rate-limiting step for production of all adrenal steroid hormones
The last common precursor is the 21-carbon molecule pregnenolone
Further biosynthesis depends upon the enzyme contents of the cell
Zona glomerulosa
Pregnenolone is metabolised to progesterone by 3β-hydroxysteroid dehydrogenase
Progesterone undergoes further hydroxylation and oxidation to aldosterone
Zona fasciculata
Here pregnenolone is also metabolised to progesterone by 3β-hydroxysteroid dehydrogenase
However, the enzyme metabolises progesterone to 17-hydroxyprogesterone
This undergoes hydroxylation steps to cortisol
Zona reticularis
Pregnenolone is acted upon directly by 17ɑ-hydroxylase, generating 17-hydroxypregnenolone
This undergoes lysis by 17,20-lyase to DHEA
Similarly to the zona fasciculata, pregnenolone also undergoes metabolism to 17-hydroxyprogesterone
Unlike the zona fasciculata, however, it instead too undergoes lysis by 17,20-lyase to androstenedione
Both DHEA and androstenedione undergo further metabolism (by both 3β- and 17β-hydroxysteroid dehydrogenase) to the sex hormones, testosterone and oestradiol