Endocrine Physiology Flashcards
In what chemical form is cholesterol typically transported in serum?
typically transported in serum as a cholesterol ester with a fatty acid at the third carbon of the cholesterol structure.
What is the primary physiological role of glucocorticoids?
The primary physiological role of glucocorticoids is the regulation of energy metabolism.
What is the primary physiological role of sex hormones?
regulation of sexual development and function
minearlocorticoid GR type 1
binds aldosterone and cortisol, but cortisol is enzymatically converted to an inactive form in aldosterone sensitive cells.
What are the major steroid hormone classes and their functions?
- glucocorticoids, affect energy metabolism
- mineralocorticoids, affect electrolyte balance
- sex hormones- affect sexual development and function
What are the groups of the nuclear receptor superfamily?
group 1- classic steroids
group 2- thyroid/retinoid/vit D/PPAR
group 3- orphans
SERM
Selective Estroen-Receptor Modulators
Estradiol (agonist)
uterus-mitogenic
breast-mitogenic
bone-increases
Raloxifene
uterus-NA
breast-
bone-increases
Tamoxifen
uterus-mitogenic
breast-differtiates
bone-NA
Complete antagonist
uterus-NA
breast-diff
bone-NA
Syndrome of Apparent Mineralocorticoid Excess
dx: symptoms of excess aldosterone, hypertension
BUT normal [aldo]
cause: excessive licorice consumption
bc licorice blocks a 11B-HS so cortisol is not inactivated and binds to the receptor
Which hormone(s) are produced in the Zona Fasciculata of the Adrenal Cortex in a healthy adult?
cortisol
DHEA
DHEAS
Which hormone(s) are produced in the Zona Glomerulosa of the Adrenal Cortex in a healthy adult?
aldosterone
Which way does blood flow between the adult Adrenal Medulla and Adrenal Cortex flows?
Centripetal: From the Adrenal Cortex to the Adrenal Medulla
Which enzyme is responsible for the rate limiting committed step of steroid synthesis?
Which enzyme is responsible for the rate limiting committed step of steroid synthesis?
Why does the adult Zona Glomerulosa produce only aldosterone?
Because it lacks the enzyme P450-17alpha, which is required for cortisol and adrenal androgen synthesis.
Congenital adrenal hyperplasia (in most cases caused by enzyme deficiency of 21-hydroxylase, aka P450-21) is characterized by what?
- decreased cortisol and aldosterone
- increased testosterone and estradiol
What causes hyper-pigmentation of the skin in Addison’s disease?
decreased cortisol -> increased ACTH -> increased pronetior, propriomelanocortin -> increased MSH and hyperpigmentation
In complete deficiency of 21-hydroxylase (P450-21), what are cortisol levels?
absent
Congenital adrenal hyperplasia
cause: deficiency in 21-hydroxylase(p450-21)
symptoms:
no cortisol or aldosterone production
high ACTH -> high adrenal androgens (androgenital syndrome for Fs, early puberty for Ms)
tx: glucocorticoids
Addison’s Disease
cause: atrophy or
dysgenesis of the adrenal, possibly autoimmune attack or TB or ACTH receptor abnormality
symptoms: decreased cortisol (fatigue, weakness, weight loss, nausea, hypoglycemia) increased ACTH (hyperpigmentation) decreased aldosterone (decreased Na -> hypotension, increased K -> arrythmia)
tx:
Cushing’s Syndrome
cause: high cortisol
(exogenous glucocorticoids AKA latrogenic, adrenocortical tumor, ACTH or CRH tumor)
symptoms: weight gain
red skin, moon face
hyperglycemic
increased aldosterone (increased Na -> hypertension, decreased K -> inverted T-waves)
tx:
The neural input that regulates chromaffin cells primarily uses which neurotransmitter:
Ach
What is present in chromaffin granules?
Epi & Nore
ATP, ADP
ascorbate
some dopamine and DBH
What is the rate limiting step for catecholamine biosynthesis?
tyrosine hydroxlase
What class of drugs formerly widely used to treat depression can cause hypertension when there are high levels of tyramines in food?
Monomine oxidase inhibitors
MAO breaks down epi and norepi, too much tyramines may replace norepi in storage vesicles -> hypertensive crisis
Which catecholamine is released at greater levels by the adrenal medulla?
Epi
This is due to 7-8 fold greater number of chromaffin cells that have phenylethanolamine-N-methyltransferase (“A-cells”) as the terminal catecholamine biosynthetic enzyme rather than dopamine-beta-hydroxylase as the terminal catecholamine biosynthetic enzyme (“N-cells”).
