Adrenal Physiology Flashcards
Glucocorticoid pathway/heirarchy
CRH: corticotropin releasing hormone from hypothalamus
ACTH: adrenocoarticotropic hormone from anterior pituitary
cortisol: principle glucocorticoid from medulla, ie hydrocortisone
Ectopic ACTH production may come from this tumor commonly
small cell lung cancer
Glucocorticoid receptors: substrate affinity
cortisol
expressed in almost all cells
Mineral corticoid receptors: substrate affinity
equal for mineralcorticoids and glucocorticoids
- *that’s dumb
- *so in aldosterone-sensitive tissues, an enzyme converts cortisol –> cortisone, which is also active and binds the mineralcorticoid receptor –> overactivation due to high concentration
- *that way, aldosterone can bind the mineralcorticoid receptor
- *licorice active ingredient inhibits this enzyme
Aldosterone effects
binds SRE in collecting duct
increases ENaC and ROMK expression
increases Na reabsorption
increases K secretion
Deficiency in aldosterone
hypernatremia
hypokalemia
Physiologic effects of glucocorticoids
increase glucose
increase free FA
increase proteolysis
decrease osteoblast activity, increase osteoclast activity
Physical findings of Cushings
central obesity thin extremities thin skin fat pad ie buffalo hump hypertension
Iatrogenic Cushing lab findings
cortisol
ACTH
increased cortisol
decreased ACTH
Secondary Cushings (pituitary origin) lab findings
cortisol
ACTH
increased cortisol
increased ACTH
What stimulates aldosterone production
ATII
Feedback stimulus for aldosterone production
Na and K concentrations
What controls plasma K concentrations
aldosterone
Addison’s disease
1˚ adrenal insufficiency
immune-mediated destruction of cortex
-decreased cortisol
-decreased aldosterone
Electrolytes in Addison’s
- hyponatremia
- hyperkalemia
