Adrenal Physiology Flashcards
3 layers of adrenal cortex
glomerulosa, fasciculata, reticularis
glomerulosa makes ___
aldosterone
fasciulata produces ____
glucocorticoids
reticularis produces ____
androgens
medulla produces _____
adrenaline
GFR salt sugar sex
mnemonic for adrenal cortex layers
Adrenocorticol hormones are produced where?
p450 in mitochondria and smooth ER of adrenal gland
Rate limiting step in steroidgenesis is ____
scc enzyme cleavage of cholesterol to pregnenolone by CYP11A1
Corticosterone is converted to aldosterone by
aldosterone synthase –> glomerulosa cells only
Aldosterone is released in response to (3) ____
increased: angiotensin 2, serum potassium, and ACTH
Cortisol is released in response to (2) ____
increased: ACTH and arginine vasopressin
Androgens are released in response to ____
increased ACTH
Norepi and epinephrine are released in response to _____ and its synthesis is dependent on high local concentrations of _____
sympathetic nervous system activation and cortisol
Aldosterone binds to ____ receptor to regulate ___ (2)
mineralocorticoid: blood volume and salt/water homeostasis
Cortisol binds to ____ receptor to regulate ____ (2)
glucocorticoid receptor: energy balance, cv, metabolic, immune homeostasis
Androgens bind ____ receptor and regulate ___
androgen: pubarche
norepi/epi bind ___ receptors to regulate ___ (2)
adrenergic: cv and bronchial dilation
______ senses blood volume, salt concentration in kidney
juxtaglomeruler cells
Renin is released in response to _____ (2)
decreased afferent arteriole volume (low renal perfusion) and decreased distal tubule sodium concentration (tubuloglomerular feedback)
Renin is decreased in response to ____ (2)
increased afferent arteriole volumea nd increased distal tubule sodium concentration
Potassium and angiotensin II sstimulate _____ in the zona glomerulosa
aldosterone synthetase
Renin
converts angiotensin to angiotensin I
ACE
converts angiotensin I to angiotensin II
Effect of aldosterone
increased Na reabsorption/water absorption, K+ and H+ secretion –> increase blood volume, decrease blood potassium concentration
Increased circulating K induce production of aldosterone which promotes Na reabsorption in exchange for K in the _______ of the nephron
distal tubule and collecting duct
- feedback for renin system
increase in BP turns off renin production and reduces production of vasoconstrictor angiotensin ii
T/F angiotensin ii induces production of aldosterone via direct effect on adrenal gland.
T
T/F cortisol has negative feedback on both ACTH and CRH
T
Stimulants of ACTH
CRH, vasopressin, inflammation
ACTH specific receptor is _______ on _____
melanocortin 2 receptor on adrenal tissue
ACTH receptor functions
increase LDL receptors to bring in more cholesterol for steroid hormones, activate CYP11A1 for cholersterol scc
T/F ACTH can function as melanocortin
T –> conserved sequence which allows it to activate melanocortin 1 receptor on melanocytes –> high ACTH can stimulate pigment production
T/F cortisol rapidly declines after awakening
T
At what time of day do we measure cortisol in order to determine adrenal insufficiency
7-8am
At what time of day do we measure cortisol in order to determine adrenal overactivity
midnight
Cortisol effect on: liver
gluconeogenesis, decrease glucose uptake
Cortisol effect on: skeletal muscle
release AA, insulin resistance (Blocks glucose uptake)
Cortisol effect on: immune
decrease macrophage, T cell, mast cell activity (antihistamine)
Cortisol effect on: bone
increase osteoclast, decrease calcium absorption –> osteoporosis
Cortisol effect on: adipose
release ffa and glycerol
Cortisol effect on: heart
increase bp via vasoconstriction, increase adrenergic receptor responsiveness
Cortisol effect on: vascular smooth muscle
vasomotor tone, responsiveness to vasoconstrictors
Cortisol effect on: adrenal medulla
epinephrine synthesis (PNMT activation)
T/F mineralocorticoid receptor has more affinity for cortisol than aldosterone
T
11beta HSD2
converts cortisol to cortisone (shunt) for mineralocorticoid rich tissue –> ensures aldosterone can have an effect in tissues like kidney
11betahsd1
reverses 11betahsd2 in tissues like liver to ensure cortisol has more impact
licorice moa
inhibits 11betahsd2 –> lots of cortisol –> hypertension, hypokalemia (psuedohyperalodsteronism)
adrenal androgens (3)
dhea, dheas, androstenedione
T/F increase in adrenal androgens with age
T
T/F andrenarche begins years before gonadarche
T
In peripheral tissues, androstendione is converted to ____ (2)
testosterone and estrone
main site of androgen production in women
adrenals
main site of androgen production in men
testes (adrenals are minor)
Adrenal medulla receives input form SNS through preganglionic fibers from _____ spinal cord
thoracic
T/F medulla lacks synapses from postganglionic fibers
T –> releases secretions directly into blood
Rate limiting step in catecholamine synthesis
tyrosine –> dopa via tyrosine hydroxylase
T/F cortisol promotes epinephrine synthesis
T –> upregulates PNMT for production of epinephrine from norepinephrine
epi/norepi production ratio in adrenal medulla
80/20
Metanephrines
not nuclear receptors–> surface membrane receptors
T/F catecholamines and metanephrines have a short half life in blood
T –> signal through second messenger systems –> not nuclear receptors
Location: alpha 1 adrenoceptor
arterial/venous vasculature: increase IP3 (vasoconstriction, increased bp)
Location: alpha 2 adrenoceptor
arterial/venous vasculature and nerve terminals: decrease cAMP
Location: beta 1 adrenoceptor
heart, juxtaglomerular apparatus: increase cAMP
Location: beta 2 adrenoceptor
heart, skeletal muscle vasculature, bronchial smooth muscle: increase cAMP –> bronchodilation, vasodilation)
__________ the principal mineralocorticoid, is produced in the ______ and released in response to ____ and ____ and acts on the collecting tubule to increase sodium reabsorption in exchange for _____ and ___ ion, therby restoring _____ and lowering serum ____ concentrations
Aldosterone, zona glomerulosa, hyperkalemia and angiotensin II/ACTH, +/H+, intravascular volume, and lowering serum potassium
______, the principal glucorticoid is produced in the _______ and is released in response to ____, acting to maintain serum ____ concentration, maintain vascular _____, and to attenuate ______
cortisol, fasciularis/reticulata, ACTH, serum glucose, vascular resistance, inflammatory/immune/wound repair response
____ (3) , the principal androgens from the adrenals are produced in ____ and released in response to ____ and ____ is converted in peripheral tissues to ____ and ____, sex hormones.
DHEA,DHEAS, and androstenedione, zona reticulata, ACTH, androstenedione to testoerone and estrone
_____ (2) are the principal catecholamines and produced in the ______ and released in response to ____ stimuli to produce _____ and _____. ___ also increases ___ production by stimulating PNMT.
norepi/epi in the medulla, SNS stimuli to produce bronchial dilation and vascular resistance, cortisol increases epinephrine production