adrenocortical hormones Flashcards
2 distinct parts of adrenal gland
inner adrenal medulla
outer adrenal cortex
adrenal medulla secretes
epinephrine and
norepinephrine
adrenal cortex secretes
corticosteroids
primary corticosteroids secreted by adrenal cortex
mineralocorticoids
glucocorticoids
sex hormones
3 distinct layers of adrenal cortex
zona glomerulosa
zona fasciculata
zona reticularis
major product of z. glomerulosa
aldosterone
primary contollers of aldosterone secretion
angiotensin II and potassium
why zona glomerulosa can’t synthesize cortisol or sex hormones
it lacks enzyme 17 hydrolase
z fasciculata secretes
glucocorticoids and corticosterone
major controller of cortisol secretion
ACTH
z. reticularis secretes
sex hormones and some glucocorticoids
most prevalent adrenal androgens
dehydroepiandrosterone (DHEA) and androstenedione
adrenocortical hormones are synthesized from
cholesterol
rate limiting step in the synthesis of adrenocortical hormones
side chain cleavage of cholesterol to form pregnenolone
conversion of cholesterol to pregnenolone occursin
ER or mito
adrenocortical hormones are bound to
plasma proteins
cortisol is bound to pp esp
transcortin or corticosteroid binding globulin
what is the result of the high degree of binding of cortisol to pp
it has a long half life
half life of aldosterone
20 minutes
primary mineralocorticoid secreted by adrenal cortex
aldosterone
enzyme present in the kidneys that converts cortisol to cortisone
11B-hydroxysteroid dehydrogenase
effect of aldosterone in sodium and potassium
it increases sodium reabsorbtion and potassium secretion
aldosterone and other mineralocorticoids act on ______ to increase Na reabsortpion and K secretion
distal nephron esp. the principal cells of collecting duct
why is there a lag time between exposure of to aldosterone and its onset of action
because protein synthesis is required to mediate the tubular actions of aldosteron
Na reabsortption and K secretion occurs after what event
it occurs after binding of aldosterone to intracellular receptors and subsequent synthesis of proteins
as sodium is reabsorbed under the influence of aldosterone, there is enhanced ___________
tubular secretion of K ions
aldosterone also causes secretion of _____ in exchange for Na in the intercalated cells of the _______
H ions; cortical collecting tubules
Aldosterone increases Na reabsorption from the _____ and promotes K excretion in the ______
colon; feces
angiotensin II stimulates the cells of
z. glomerulosa
the effect of A II is meiated vie
increments in intracellular levels of Ca and phosphatidyl inositol products diacylglycerol and inosital 3P
2nd msgers activate protein kinase C which in turn stimulates
early and late steps in biosynthesis is aldosterone
control of aldesterone secretion by A II is closely linked to the regulation of
ECF volume and arterial pressure
RAS is activated in the presence of
hypovolemia and hypotension
increase in plasma K conc increase adlosterone secretion by
depolarizing the cell mem, opening Ca channels thereby increasing intracellular Ca conc
Inc in K conc increase aldosterone secretion which in turn stimulates
tubular secretion of K
if ACTH is chronically deficient, aldosterone response to ________ and_______ is diminished
A II and K
high plasma levels of ACTH stimulates
aldosterone secretion
effects of cortisol on metabolism
- decreases protein stores in extrahepatic tissues
- increase blood glucose conc
- plays an important role in mobilization of FA from adipose tissue
how does cortisol decrease protein stores
it decreases amino acid uptake and inhibits protein synthesis, at the same time it increases protein degradation
what is the result of the catabolic and antianabolic effects of cortisol
AA increases in the blood and are taken up in the liver where they are converted to glucose and proteins including gluconeogenic enzymes
how does cortisol increase blood glucose conc
it increases gluconeogenesis and it impairs the utilization of glucose in peripheral tissues
what is the role of cortisol on mobilization of FA
it allows other liplytic hormones (epinephrine and GH) to mobilize FA from lipid stores
physical and mental stress increases ACTH secretion which in turn
stimulates adrenal cortex to secrete cortisol
large doses of glucocorticoids decrease the
inflammatory response
effects of glucocorticoids in the inflammatory response
- inhibition of phospholipase
- stabilization of lysosomal membranes
- suppresion of the immune system
- inhibition of fibroblastic activity
