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Adrenal gland - Functional anatomy

Adrenal gland - They are suprarenal - they sit on top of the kidneys.
Each is composed of 2 distinct regions:
A. Adrenal Medulla
- the inner region
- comprises 20% of the gland
- secretes epinephrine and norepinephrine
- derived from ectoderm 
B. Adrenal Cortex
- the outer region
- comprises 80% of the gland
- secretes corticosteroids 
- derived from mesoderm

Following are the parts of adrenal cortex

  1. Zona Glomerulosa (outermost region) - produces mineralocorticoids (aldosterone)  
  2. Zona Fasiculata (middle region) - produces glucocorticoids (cortisol) as well as estrogens and androgens.
  3. Zona Reticularis (innermost region)  produce  adrenal androgens.