Flashcards in Adrenal Physiology Deck (24):
What does each section of adrenal secrete?
F: Glucocorticoids (cortisol)
Adrenocorticoids are synthesized from ____ by _____
Adrenocorticoids are synthesized from cholesterol by cytochrome P450
What are steps
Which hormone can only be made in one area of adrenal gland? Why?
Aldosterone can only be made in zona glomerulosa because only those cells have aldosterone synthetase
What is the function of Aldosterone? (2) What are stimulants for Aldosterone release? (3)
Function of aldosterone: regulate blood volume, salt/water homeostasis
Stimulators: Angiotensin II, [K], ACTH (to lesser degree)
What is the function of cortisol? (2) What are stimulants for cortisol release? (2)
Functions of cortisol: energy balance, CV/metabolic/immune homeostasis
Stimulators: ACTH, Arginine vasopressin (lesser stimulus)
What is function of androgens? (1) What is stimulant for androgen release? (1)
Function: Regulate pubarche
What are functions of NE/epinephrine (2)
Regulate CV effects
Regulate bronchial dilation
What is mechanism of Aldosterone?
Aldosterone binds mineralocorticoid receptor in distal collecting duct of principal cell
Moves to nucleus to stimulate transcription of Na/K channels-->More Na reabsorption, K/H+ secretion
What are stimulants of CRH? (2)
Circadian rhythm, physical stressors
What are stimulants of ACTH (3)?
CRH, inflammation, arginine vasopressin
What are functions of ACTH? (2) Explain its melanogenic properties
Functions: Increase LDL receptors to bring in more cholesterol as precursor for steroidogenesis
Activate CYP11A1 enzyme for steroid cleavage
Functions as melanocortin by activating melanocortin 1 receptor on melanocyte (leads to skin pigmentation)
Explain cortisol secretion pattern. When is it highest/lowest?
Circadian rhythm with pulsatility.
Highest 6-8 hours after sleeping and declines after awakening
Lowest at midnight
What are cortisol actions?
Liver, skeletal muscle, adipose, Heart, vascular smooth muscle, immune, bone, medulla
Lots and lots...know list
Explain cortisol-cortisone shunt
Mineralocorticoid receptor has higher affinity for cortisol than aldosterone
In kidney (aldosterone sensitive tissue), shunt cortisol to cortison
Explain how cortisone is converted back to cortisol
Cortisone in liver (GCR rich tissue) is converted back to cortisol
Explain pseudohyperaldosteronism and licorice
Licorice prevents inactivation of cortisol in kidney
Cortisol activates MCR-->hypertension and hypokalemia
What are functions of DHEA and androstenedione?
DHEA: stimulates pubarche
Androstenedione: converted to testosterone and estrone in peripheral tissues
Explain catecholamine synthesis
Tyrosine enters chromatin cells and is converted by TH to dopa. Dopa then converted to NE/epinephrine
What is rate limiting step of catecholamine synthesis?
Tyrosin to DOPA via tyrosine hydroxylation
What promotes NE to epinephrine conversion? How does it work?
Cortisol upregulates PNMT enzyme which converts NE-->Epinephrine
How much of catecholamines does medulla secrete?
What do catecholamines bind? What are the locations and effects?
Bind adrenergic receptors (a1/a2/ß1/ß2)
Too many locations and effects to list