Adrenal Insufficiency and Cushings Flashcards
Adrenal Gland lie in the_______ above or medial to the upper pole of the kidneys. The adrenal cortex differentiates into three adult zones: glomerulosa (______) and fasciculata/reticularis (_____and_____)
retroperitoneum
aldosterone
cortisol and androgens
The adrenal_____ is richly vascularized receiving its main arterial supply from branches of the inferior phrenic artery, the renal arteries and the aorta.
cortex
What is the difference beteween the drainage of right and left adrenal glands?
The right adrenal vein drains directly into the posterior aspect of the vena cava and the left adrenal vein enters the left renal vein.
What could cause bilateral adrenal hemorrhage?
a coagulopathy resulting in bilateral adrenal vein thrombosis.
Steroid production from the zona fasciculata and reticularis is controlled by the pituitary hormone_____ whose secretion is regulated by the hypothalamus and central nervous system via neurotransmitters and ________ and by negative feedback.
ACTH
corticotroph-releasing hormone [CRH and arginine vasopressin (AVP)]
CRH stimulates ACTH in a
pulsatile manner. Diurnal rhythm causes a peak before awakening and a decline as the day progresses.
Pathologic conditions such as Cushing’s disease (an ACTH-secreting pituitary tumor) are manifested by deregulated______ secretion since the set point for negative feedback on______ is increased
cortisol
ACTH
Adrenocorticotropin or ACTH is a 39 amino acid peptide hormonewhich is processed from a large precursor molecule, _________within the ACTH-secreting cells in the pituitary gland corticotroph.
pro-opiomelanocortin (POMC)
The cortisol synthetic pathway requires ACTH-stimulated cholesterol import into the mitochondrion, a process initiated by the action of the __________which shuttles cholesterol from the outer to the inner mitochondrial membrane.
steroidogenic acute regulatory (StAR) protein,
The majority of steroidogenic enzymes are cytochrome P450 (CYP) enzymes, which are either located in the________ (side chain cleavage enzyme, CYP11A1; 11-hydroxylase, CYP11B1; aldosterone synthase, CYP11B2) or in the_________ (17- hydroxylase, CYP17A1; 21-hydroxylase, CYP21A2)
mitochondrion
endoplasmic reticulum membrane
The cholesterol side chain cleavage enzyme CYP11A1 (P450scc) generates
pregnenolone
Glucocorticoid synthesis requires conversion of pregnenolone to progesterone by what enzyme
3-beta-hydroxysteroid dehydrogenase (3-βHSD2)
Cortisol binds to plasma proteins on entering the circulation. At physiological concentrations, cortisol circulates in the plasma bound mainly to _______, and to a much lesser extent to albumin.
corticosteroid-binding globulin (CBG
The measurement of this free cortisol can be done in
saliva and is independent of salivary flow rates.
used clinical application for the assessment of the hypothalamic-pituitary-adrenal axis particularly in states of suspected hypercortisolism.
Cortisol is metabolized to biologically inert steroid cortisone by the enzyme_______ in the kidney to protect the mineralcorticoid receptor as cortisol has same affinity for that receptor as aldosterone
11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2).
prodigious increases in cortisol secretion may overwhelm the intrarenal metabolism of cortisol in the kidney causing significant mineralocorticoid effects such as
hypertension and hypokalemia
seen in pts with Cushings
how does the liver handle cortisone?
uses 11B-HSD1 takes it to cortisol
What are the two mechanisms of action of cortisol?
GR Transrepression (depresses genes that work in inflammation)
GR Transactivation
Utilization of a glucocorticoid receptor antagonist,________, has emerged as an effective therapy for the treatment of endogenous hypercortisolism
mifepristone
The progesterone compound,____________ may be used to actually stimulate appetite in cancer patients and has been shown to cause suppression of ACTH and cortisol
megestrol acetate,
What are the main targets and actions of clucocorticoids and consequences of hypercortisolism and hypocortisolism
Intermediary metabolism, calcium homeostais, other endocrine systmes, immune system, skin and CT, CV system, Na+, K+ and ECF volume and pysch
Inadequate production of cortisol from the adrenal cortex may be caused by either a disease process in the adrenal gland :_________or due to diseases of the pituitary gland :__________ or hypothalamus __________
(primary adrenal insufficiency)
(secondary adrenal insufficiency)
(tertiary adrenal insufficiency)