37 - Adrenals Flashcards
Embryological origin of the adrenals, gonads and kidneys
Embryonic ridge
What does the embryonic ridge spilt into
Adrenogonadal primordium
and neural crest cells
- forms foetal adrenal which has 4 zones
Zones of the adrenals from outermost to inner
Zona glomerulosa
Zona fasciculata
Zona reticularis
Where are the adrenals and what are they made up of
Above the kidney
Made up of adrenal cortex and medulla
Blood supply of the adrenal gland
Flows in from the capsule and flows centrally
Blood is exposed to cortisol produced in zona fasciculata
Blood supply into adrenal medulla has been exposed to steroids
Hormone from Zona glomerulosa + receptor
Adosterone
CYPIIB2
Hormone from Zona fasciculata + receptor
Cortisol
CYPIIBI
Hormone from Zona reticularis + receptor
Testosterone
CYPI7AI
What is the function of aldosterone
Vasoconstriction
K+ Secretion
Na+ re absorption
= Increases BV
Hyperaldosterism
Low K+
High BP
Metabolic Alkalosis
Hypernatremia
Where is the mineralcorticoid receptor
In nucleus almost everywhere
What does the mineralcorticoid receptor bind to
Cortisol and aldosterone
What converts cortisol to cortisone in the kidney
11BHS2
Why is cortisol converted to cortisone
As more cortisol in the blood
Cortisone doesn’t active the receptor and allows for aldosterone to bind too
What does aldosterone bind to in the kidney
Mineralcorticoid receptor in principle cell in distal convulated tubule
What does aldosterone do in the kidney DCT
Activate Na+/K+ ATPse
Upregulates ENaC so Na reabsorbed and K+ excreted
Cl- absorbed to maintain neutrality
What does aldosterone do in in the intercalated cells (A and B cells)
Binds to the MR receptor
Activates Na+./K+ pump
Activate H+/K+ ATPase causes loss of H+ –> acid urine and alkalotic blood
Conn’s Syndrome
Primary hyperaldosterism
- Hypertension
- Suppressed plasma renin activity
- increased aldosterone secretion
- Aldosterone producing adenoma, bilateral adrenal hyperplasia
How do you diagnose Conn’s syndrome
Aldosterone:renin ration Saline suppression test(to try and suppress aldosterone) CT adrenal Adrenal venous sampling Metomidate PET
What can cause glucocorticoid remediable aldosteronism
Aldosterone synthase and 11 B hydroxylase can cross over and form a mutated gene
ACTH activates promotor of 11B hydroxylase and increases aldosterone
What is glucocorticoid remediable aldosteronism
Low potassium
High BP
Met alk
How do you treat GRA
Steroids
Can suppress ACTH and so suppresses aldosterone
What does liquorice inhibit and what does it do
11BHSD2
Stops activation of cortisol
How can cortisol cause hyperaldosterism
Cortisol binds to MR
Can lead to syndrome of apparent mineralocorticoid excess
Liddle syndrome
Mutation which increases ENaCs
Hypertension, hypokalaemia, metabolic acidosis
Low aldosterone
What does the HPA axis respond to
Stress
Where is corticotropin-releasing hormone released
Hypothalamus