47: HPA Axis: Adrenals Flashcards
What is ACTH derived from?
POMC
What causes hyperpigmentation seen in Addison’s disease?
Excess ACTH -> increases melanin synthesis
What does DHEAS stand for?
Dehydroepiandrosterone sulfate
What is epi complexed with when stored in chromaffin granules?
ATP, Ca, chromogranins
Chromogranins function
Decrease osmotic burden of storing E granules
What does circulating chromogranins signal?
Sympathetic paraganglionic derived tumors
What does cortisol upregulate in the adrenal medulla?
PNMT -> more epi produced from norep
What does Ach do in adrenal medulla?
Stimulates synthesis of catecholamines
Three things to measure in blood to determine total catecholamine production
- Catecholamines
- Metanephrines
- Vanillylmandelic acid (VMA)
Two enzymes that break down catecholamines
COMT, MAO
which adrenergic receptors respond more to norep? Which one responds more to epi? Which responds equally?
Norep: A1, A2, B3
Epi: B2
Equal: B1
A1 receptor function
Increase vascular smooth muscle contraction
A2 receptor function
Inhibits norep and insulin release
B3 receptor functions
Increase lipolysis, increase hepatic glucose output
B2 receptor function
Increase glucose output from liver, vasodilation, work on bronchioles and uterus
B1 receptor function
Increase cardiac output
What causes pseudo-cushing’s syndrome?
Major depression and anxiety, acute/chronic illness, sometimes alcoholism
How to detect adrenal insufficiency?
Cosyntropin (synthetic ACTH) stimulation test
What causes Waterhouse-Friedrichsen syndrome?
N. Meningitidis or anticoagulants -> adrenal hemorrhage
Axis that helps create aldosterone
Renin-angiotensin-aldosterone
Treatment for primary and secondary adrenal insufficiency
Primary: replace cortisol and aldosterone
Secondary: replace cortisol
