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41 Cards in this Set

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What is the embryological origin of the adrenal medulla?
neuroectoderm
What is the embryological origin of the adrenal cortex?
mesoderm
What are the layers of the adrenal cortex (from outside to in), and what hormones do they each primarily secrete?
Zona glomerulosa (mineralocorticoids-aldosterone)
Zona fasciculata (glucocorticoids-cortisol)
Zona reticularis (androgens-dehydroepiandrosterone(DHEA) and androstenedione)
What is the first step in the biosynthetic pathway of steroid hormones? What factor stimulates this step?
Cholesterol (via cholesterol desmolase) -> pregnenolone

Stimulated by ACTH
What hypothalamic and a/p hormones regulate the release of glucocorticoids, androgens, and mineralocorticoids?
ACTH and CRH (for glucocort and androgens)

for mineralocorticoids: depends ACTH (no a/p control), and is controlled separately by renin-angiotensin-aldosterone system
What is the pattern of cortisol secretion (when is it highest/lowest?)
pulsatile nature, diurnal pattern; oscillates with circadian rhythm (highest ~8am, lowest ~12am)

*is driven by the diurnal pattern of ACTH secretion (which in turn, is driven by CRH burst)*
What are the effects of ACTH?
stimulate cholesterol desmolase, up-regulates its own receptor, and when chronically increased, causes hypertrophy of adrenal cortex
What negative feedback mechanisms are present for the secretion of cortisol?
cortisol inhibits CRH release from hypothalamus and secretion of ACTH from a/p
Pt is given a dexamethasone suppression test. Low dose does not suppress cortisol, but high does does. What might the disorder be?
ACTH-secreting tumor
Pt is given a dexamethasone suppression test. Neither low dose nor high dose suppresses cortisol. What might the disorder be?
adrenal cortical tumor (secretes cortisol)
Is aldosterone regulated by ACTH?
yes, it is under tonic control by ACTH
Pt becomes volume depleted. Describe the cascade that follows.
Dec ECF -> dec perfusion pressure -> inc renin -> catalyzes angiotensinogin to angiotensin I -> (via angiotensin converting enzyme (ACE)) to angiotensin II -> stimulates corticosterone to aldosterone in zona glomerulosa -> inc Na r/a, inc K s/c -> inc ECF
Pt becomes hyperkalemic. What is the hormonal response?
K depolarizes adrenal cells, opens Ca channels, Ca rushes in, stimulates aldosterone s/c
What are the metabolic effects of glucocorticoids (cortisol)?
Overall, effects are catabolic and diabetogenic: stimulates gluconeogenesis, inc protein catabolism in musc and dec new protein synthesis (provides addnl AA to liver for gluconeo), inc lipolysis (addnl glycerol to liver), dec gluc utilization by tissues, dec insulin sensitivity of adipose tissue
What happens to glucose levels in hypocortisolism? In hypercortisolism?
hypocortisolism -> hypoglycemia

hypercortisolism -> hyperglycemia
What hormone mediates the stress response?
cortisol (glucocorticoids)
What adrenocortical steroid is critical for survival during fasting?
cortisol (glucocorticoids)
What are the effects of cortisol on the immune system?
Anti-inflammatory and immunosuppressive:
-induces synthesis of lipocortin, which inhibits phospholipase A2 (key for AA metabolism), thus inhibits precursor of leukotrienes and prostaglandins
-inhibit IL-2 and T cell proliferation
-inhibits release of histamine and 5HT from mast cells and platelets
What are the vascular effects of cortisol?
up regulates alpha-1 adrenergic receptors, required for vasoconstrictive response to NE

(hypocortisolism -> hypotension; hypercortisolism -> hypertension)
What are the actions of mineralocorticoids (aldosterone), and what cell types mediate these effects?
-principal cells of late distal tubule and collecting ducts -> inc Na r/a and K s/c
-alpha-intercalated cells of LDT and CDs) -> inc H s/c
What role do adrenal androgens (DHEA and androstenedione) play in males?
small role; converted to testosterone in testes (but most testosterone is synthesized de novo in testes)
What role to adrenal androgens (DHEA and androstenedione) play in females?
important for pubic and axillary hair, and libido
What is adrenogenital syndrome? What are the sx?
inc synthesis of adrenal androgens; masculinization of females, early hair development, and suppression of gonadal fn in males and females
Sx: weight loss, weakness, nausea, hyperpigmentation, low bp, high K, metabolic acidosis, hypoglycemic upon fasting, dec pubic/axillary hair in females, high ACTH levels

What is the cause? What is the disorder?
Low aldosterone, cortisol, and adrenal androgens

Primary adrenocortical insufficiency (Addison's Disease): autoimmune destruction of all zones of adrenal cortex
What causes hyperpigmentation in Addison's disease?
increased levels of ACTH from negative feedback (which contains the alpha-MSH fragment)
What is the treatment for Addison's disease?
Glucocorticoid and mineralocorticoid replacement
Sx: weight loss, nausea, weakness, hypoglycemia, low ACTH levels

What is the cause? What is the disease?
Insufficient ACTH levels (from failure of corticotrophs in a/p)

"Secondary adrenocortical insufficiency"

*no symptoms of hypoaldosteronism, no hyperpigmentation*
Sx: hyperglycemia, central obesity, round face, supraclavicular fat, buffalo hump, muscle wasting, osteoporosis, striae, high bp, (and virilization & menstrual d/o's in women)

What is the cause? What is the disease?
excessive glucocorticoids and adrenal androgens

Cushing's syndrome or Cushing's disease
What is the cause of Cushing's syndrome?
primary adrenal hyperplasia (spontaneous overproduction of cortisol) or exogenous glucocorticoids
What is the cause of Cushing's disease?
pituitary adenoma which causes hypersecretion of ACTH
What test can differentiate between Cushing's syndrome and Cushing's disease? How will the results differ?
dexamethasone suppression test

Cushing's syndrome (LOW ACTH): neither low nor high dose can suppress cortisol levels

Cushing's disease (HIGH ACTH): not low dose, but high dose can suppress cortisol levels
What is the the treatment for Cushing's sydrome?
drugs that block steroid biosynthesis (ketoconazole or metyrapone)
What is the treatment for Cushing's disease?
surgical removal of ACTH-secreting tumor
Sx: hypertension, hypokalemia, metabolic alkalosis, decreased renin levels

What is the disturbance? What is the disease?
aldosterone secreting tumor -> Conn's syndrome
What is the treatment for Conn's syndrome?
aldosterone antagonist (spironolactone), followed by surgical removal of aldosterone-secreting tumor
How can symptoms of increased adrenal androgens, but decreased glucocorticoids and mineralocorticoids be explained?
21 beta-Hydroxylase deficiency (a type of adrenogenital syndrome)

progesterone and 17-hydroxyprogesterone cannot be converted to the steroid intermediates that lead to mineralocort's and glucocort's. thus all steroid intermediates above block are shunted toward production of adrenal androgens
Will ACTH levels be increased or decreased in 21 beta-Hydroxylase deficiency?
increased (negative feedback effect of cortisol)
How can sx of increased mineralocorticoids, but decreased adrenal androgens and glucocorticoids be explained?
17 alpha-Hydroxylase deficiency

pregnenolone and progesterone cannot be converted to the steroid intermediates that lead to andrenal androgens and glucocort's. thus all steroid intermediates above block are shunted toward production of mineralocorticoids.
Will ACTH levels be increased or decreased in 17 beta-Hydroxylase deficiency?
increased (negative feedback effect of cortisol)
What is the treatment for 21 beta-Hydroxylase deficiency?
replacement of mineralocorticoids and glucocorticoids
What is the treatment for 17 beta-Hydroxylase deficiency?
replacement of glucocorticoids and aldosterone antagonist