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liveonearth) wrote2009-07-22 12:23 pm
liveonearth) wrote2009-07-22 12:23 pm
Adrenal Basics: Anatomy and Physiology
If a person has hypopituitarism, what effect would you expect on the adrenals?
The zona fasciculata and zona reticularis, which are both normally activated by ACTH from the ant pit, would atrophy, so that you'd have less adrenal production of cortisol and sex steroids. The glomerulosa (produces aldosterone) and the medulla (produces dopa, epi and nor-epi) would be unaffected.
GENERAL
aka suprarenal glands
sit on top of kidneys
make corticosteroids (cortisol), mineralocorticoids (aldosterone) and catecholamines (dopa, epi & nor-epi)
also sex steroids (DHEA, progesterone, estrogen, testosterone)
surrounded adipose capsule and the renal fascia
located at about T11-12
R side lower due to liver taking up space
MEDULLA
chromaffin cells (derived from neural crest) are main source of catecholamines
catecholamines are water soluble, derived from aa tyrosine
adrenal medulla is from ectoderm tissue in embryo
considered specialized ganglia of the sympathetic nervous system
releases hormones into the blood
main source of dopamine, precursor of epi & norepi
CORTEX
makes corticosteroid hormones from cholesterol
HPA axis controls cortisol/corticosterone synthesis
normal production: 35–40 mg of cortisone acetate per day
also makes androgens, testosterone
also regulates water and electrolyte concentrations via aldosterone
cortex regulated by neuroendocrine hormones from pituitary gland and by renin-angiotensin system (ALD)
THREE LAYERS OF CORTEX: ZONAS
from outermost in:
ZONA GLOMERULOSA
mineralocorticoids including aldosterone
ald release provoked by RAA system, triggered by low blood volume
ALD-->distal convoluted tubules excrete K+, reabsorb Na+ and H2O-->increase volume and BP
licorice works to increase BP by increasing mineralocorticoid production
ZONA FASCICULATA
glucocorticoids incl cortisol and corticosterone
stimulated by ACTH from ant pit-->incr cAMP
some cortisol secretion persists even when there's not ACTH
ZONA RETICULARIS
makes DHEA in response to ACTH signal from ant pit which is controlled by hypothalamic signal
other sex steroids too: est, test,
DHEA = dehydroepiandrosterone
CIRCULATION
tied with thyroid for greatest blood supply/gram of tissue
up to 60 arterioles enter each adrenal
THREE MAIN SUPPLIES
superior suprarenal artery from inferior phrenic
middle suprarenal artery direct from abdominal aorta
inferior suprarenal artery from renal artery
DRAINAGE
right suprarenal vein-->inferior vena cava
left suprarenal vein-->left renal vein or left inferior phrenic vein
suprarenal veins may anastomose with inferior phrenic veins
The zona fasciculata and zona reticularis, which are both normally activated by ACTH from the ant pit, would atrophy, so that you'd have less adrenal production of cortisol and sex steroids. The glomerulosa (produces aldosterone) and the medulla (produces dopa, epi and nor-epi) would be unaffected.
GENERAL
aka suprarenal glands
sit on top of kidneys
make corticosteroids (cortisol), mineralocorticoids (aldosterone) and catecholamines (dopa, epi & nor-epi)
also sex steroids (DHEA, progesterone, estrogen, testosterone)
surrounded adipose capsule and the renal fascia
located at about T11-12
R side lower due to liver taking up space
MEDULLA
chromaffin cells (derived from neural crest) are main source of catecholamines
catecholamines are water soluble, derived from aa tyrosine
adrenal medulla is from ectoderm tissue in embryo
considered specialized ganglia of the sympathetic nervous system
releases hormones into the blood
main source of dopamine, precursor of epi & norepi
CORTEX
makes corticosteroid hormones from cholesterol
HPA axis controls cortisol/corticosterone synthesis
normal production: 35–40 mg of cortisone acetate per day
also makes androgens, testosterone
also regulates water and electrolyte concentrations via aldosterone
cortex regulated by neuroendocrine hormones from pituitary gland and by renin-angiotensin system (ALD)
THREE LAYERS OF CORTEX: ZONAS
from outermost in:
ZONA GLOMERULOSA
mineralocorticoids including aldosterone
ald release provoked by RAA system, triggered by low blood volume
ALD-->distal convoluted tubules excrete K+, reabsorb Na+ and H2O-->increase volume and BP
licorice works to increase BP by increasing mineralocorticoid production
ZONA FASCICULATA
glucocorticoids incl cortisol and corticosterone
stimulated by ACTH from ant pit-->incr cAMP
some cortisol secretion persists even when there's not ACTH
ZONA RETICULARIS
makes DHEA in response to ACTH signal from ant pit which is controlled by hypothalamic signal
other sex steroids too: est, test,
DHEA = dehydroepiandrosterone
CIRCULATION
tied with thyroid for greatest blood supply/gram of tissue
up to 60 arterioles enter each adrenal
THREE MAIN SUPPLIES
superior suprarenal artery from inferior phrenic
middle suprarenal artery direct from abdominal aorta
inferior suprarenal artery from renal artery
DRAINAGE
right suprarenal vein-->inferior vena cava
left suprarenal vein-->left renal vein or left inferior phrenic vein
suprarenal veins may anastomose with inferior phrenic veins