- Adrenal glands
- Anatomically comprised of two distinct parts
- Medulla (30%)
- Essentially a modified sympathetic ganglion or neural crest origin
- Secretes adrenaline (~80%), NA (~20%) and small amounts of dopamine, ACh, chromogrannin A and metenkephalin
- Catecholamine synthesis occurs here (note: tyrosine to DOPA is the rate limiting step)
- Cortex (70%)
- Composed of 3 layers (mnemonic GFR), which secrete hormones (mnemonic ACTH)
- Responsible for steroid synthesis
- Steroids are derived from cholesterol
- 27 carbon cholesterol is converted to 21 carbon mineralocorticoids and glucocorticoids
- STEROID SYNTEHSIS PIC FROM WIKI
- Control of aldosterone secretion
- Mineralocorticoids (aldosterone)
- ↑Na⁺ reabsorption by kidneys, in the gut and from sweat
- ↑renal K⁺/H⁺ loss
- ↑Na⁺ channels in the DCT
- Glucocorticoids
- Have various effects on body systems
- Metabolic
- Stimulates gluconeogenesis
- Promotes protein catabolism
- Metabolism of adipose tissue
- CVS
- Role in response to vasoconstrictors
- Anti-inflammatory
- Potent anti-inflammatory actions
- ↓ macrophage migration
- ↓ cytokine production
- Thyroid
- Inhibits T4 ➝ T3 conversion
- Others
- ↑Na⁺/H₂O absorption
- ↑K⁺ excretion
- CRH (hypothalamus)
- ACTH (Anterior pituitary)
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