Endocrine Physio Flashcards
lipid soluble hormones
steroids, thyroid hormones
receptors inside the cell -> usually in nucleus
transported by binding to proteins made in the liver
water soluble hormones
peptides, proteins
receptors on outer surface of the cell membrane
what is the intracellular action of insulin
activates membrane-bound tyrosine-kinase, does not utilize cAMP
MEN syndromes: hyperfunction
a group of inheritable syndromes characterized by multiple benign or malignant tumors
MEN1
hyperparathyroidism, endocrine pancreas, and pituitary adenomas
MEN 2A
medullary carcinoma of the thyroid, pheochromocytomas, hyperparathyroidism
MEN 2B
medullary carcinoma of the thyroid, pheochromocytomas, hyperparathyroidism typically ABSENT
Sheehan syndrome
the pituitary is enlarged and therefore more vulnerable to infarction
-delivery associated with severe blood loss causes shock which causes arteriolar spasm in the pituitary with subsequent necrosis
functions of ANP
increases sodium loss (natriuresis) and water loss (diuresis) by the kidney bc it inhibits aldosterone release as well as the reabsorption of sodium and water in the collecting duct
- ANP tends to antagonize the effects of AT2 and ADH
- ANP is released in response to stretch. The major action of ANP is diuresis and natriuresis
V2 receptor antagonists
Conivaptan and tolvaptan -> they stop ADH effect on kidney tubule
hyponatremia
involves both solute depletion and water retention but water retention is usually the more important factor
- develops rapidly and severe (
central diabetes insipidus
low plasma ADH
-tx with desmopressin
nephrogenic diabetes insipidus
high plasma ADH
SIADH
inappropriate elevated secretion of ADH. characterized by euvolemia but hyponatremia
viscerosomatic reflex of the adrenal regions
T10 bilaterally
ACTH controls
the release of cortisol and adrenal androgens in the z. fasciculata and the z. reticularis, respectively
what stimulates aldosterone
a rise in angiotensin 2 and/or K+
angiotensin II is the main stimulus to the z. glomerulosa and it produces
aldosterone
glucagon
promotes glycogenolysis in the liver. w/out cortisol, fasting hypoglycemia rapidly develops. cortisol permits glucagon to break down glycogen and generate glucose from gluconeogensis
primary adrenal insufficiency: effects of skin
excessive secretion of ACTH; causes darkening of the skin due to the a-MSH sequence in the ACTH and the B-MSH activity of B-lipotropin
what do endorphins modulate
perception of pain
actions of angiotensin 2
raises BP, increases Na+ absorption and water volume, increases ADH release from the post pituitary, increases thirst, increases sodium reabsorption in proximal tubule
establishing the presence of hypercorisolism
24 hr urine-free-cortisol or 1 mg overnight dexamethasone suppression test
-a single random cortisol test is always the wrong answer
high dose dexamethasone test
differentiate pituitary adenoma from ectopic ACTH secretion and adrenal tumors
- pituitary source: cortisol decr
- ectopic ACTH, adrenal tumor: cortisol not suppressed
ACTH stimulation test
dx adrenal insufficiency
-give ACTH -> no change in cortisol levels
metyrapone testing will always be the wrong answer
.
secondary hypercortisolism: ectopic ATCH syndrome
most freq in pts with small cell carcinoma of the lung
- greater secretion of ACTH than in Cushings dz (pituitary microadenoma)
- hyperpigmentation often present
- ectopic site nonsupressible with dexamethasone
