Editing Adrenals (section)

== Histology of Adrenal Glands ==

* The gland is surrounded by a capsule
* '''<span style="color:#ff0000">Composed of 2 embryologically and functionally distinct components:'''
*# '''<span style="color:#ff0000">Outer cortex'''
*#* Makes up ≈90% of the adrenal mass
*#* '''<span style="color:#ff0000">Endocrine component'''
*#* Derived from intermediate mesoderm
*#* '''<span style="color:#ff0000">Composed of 3 layers (from outer to inner):'''
*#*# '''<span style="color:#ff0000">Zona Glomerulosa'''
*#*#* Comprises ≈15% of the cortex
*#*#* '''<span style="color:#ff0000">Produces aldosterone</span>''' as a result of unique zonal expression of aldosterone synthase (CYP11B2)
*#*# '''<span style="color:#ff0000">Zona Fasciculata'''
*#*#* '''Comprises ≈80% of the cortex'''
*#*#* '''<span style="color:#ff0000">Produces glucocorticoids</span>''' as a result of zonal expression of 17α-hydroxylase, 21-hydroxylase, and 11β-hydroxylase enzymes
*#*#** '''Cortisol is the main glucocorticoid'''
*#*# '''<span style="color:#ff0000">Zona Reticularis'''
*#*#* Comprises ≈5-7% of the cortex
*#*#* '''<span style="color:#ff0000">Produces the sex hormones</span>''' as a result of zonal expression of 17α-hydroxylase and 17,20-lyase '''(3):'''
*#*#*# '''Dehydroepiandrosterone (DHEA)'''
*#*#*# '''Sulfated DHEA (DHEA-S)'''
*#*#*# '''Androstenedione'''
*#*#* '''The sex hormones (DHEA, DHEA-S, and androstenedione) comprise the greatest portion of steroid hormone that is produced by the adrenals''' (>20 mg/day), but appear to be the least important for adult physiologic homeostasis
*#*#** Only 100-150 mcg/day of aldosterone and approximately 10-20 mg/day of cortisol are produced by the glands.
*# '''<span style="color:#ff0000">Inner medulla'''
*#* '''<span style="color:#ff0000">Neurocrine component'''
*#* Derived from neural crest cells that later give rise to chromaffin cells
*#* '''<span style="color:#ff0000">Chromaffin cells of the medulla secrete the catecholamines (3):'''
*#*# '''<span style="color:#ff0000">Epinephrine (80%)'''
*#*# '''<span style="color:#ff0000">Norepinephrine (19%)'''
*#*# '''<span style="color:#ff0000">Dopamine (1%)'''
*#** '''These catecholamines are produced from the amino acid tyrosine'''
*#** '''The adrenal gland is the primary source of systemic epinephrine'''
*#*** Despite the presence of similar chromaffin cells elsewhere in the sympathetic nervous system, the enzyme phenylethanolamine-N-methyltransferase ('''PNMT'''), which '''catalyzes the conversion of norepinephrine to epinephrine, is relatively unique to the adrenal medulla''' (the brain and organ of Zuckerkandl also express this enzyme)
[[File:1818 The Adrenal Glands.jpg|alt=Adrenal gland anatomy and histology. |center|thumb|900x900px|Adrenal gland anatomy and histology. Source: [[commons:File:1818_The_Adrenal_Glands.jpg|Wikipedia]]]]