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”).
What would an autoimmune attack of the thyroid gland lead to?
Either hypothyroid (Hashimoto’s) or hyperthyroid (Graves’) function
What do de-iodination rxns do?
activate thyroid hormones (T4 -> T3)
deactivate thyroid hormones (T3-rT3)
Congenital hypothyroidism
common -> neonatal screening
Paget’s disease
more common in men
What is the most commonly prescribed class of drugs for treating osteoporosis, and briefly in one sentence, how do they work?
Bisphophophonates. These drugs inhibit osteoclasts from further degrading bone.
Which membrane ion channel is responsible for regulating insulin release from beta cells?
The K-ATP channel, which includes SUR subunits.
Which hormones are released from the endocrine pancreas?
somatostatin, insulin, pancreatic polypeptide, glucagon
True or false, insulin up-regulates the activity of glucose-6-phosphatase in the liver?
False. Insulin promotes anabolic processes, so it up-regulates the activity of glucokinase, which has opposing biochemical actions to glucose-6-phosphatase
Which oral hypoglycemic drugs are prescribed for Type II DM?
Sulfonylureas and biguanides (including metformin) are two of the most commonly prescribed as oral hypoglycemic drugs to patients with Type II Diabetes Mellitus
What is the primary metabolic fuel for the brain during prolonged starvation
ketone bodies
What is the most useful clinical lab test commonly used to monitor long term blood glucose levels?
Hemoglobin A1c
What are the four “counter regulatory” hormones that promote glucose mobilization?
cortisol, glucagone, growth hormone, epinephrine
What hormone is the best measure of fetal well being?
estriol
What are the complications that result from hyperglycemia over long time periods?
vascular disease, retinopathy, nephropathy, neuropathy, increased infection rates, poor wound healing
Which hormones are secreted by fat cells to regulate energy metabolism?
leptin, resistin, adiponectin
Laron dwarfs
defective receptors for GH -> low IGF-1
proliferative phase
aka follicular phase
secretory phase
aka luteal phase
ovulation
day 14, peak in serum LH on day 13-14
What is the approximate probility of intercouse for: day 6 day 11 day 14 day 16
day 6: 0%
day 11:14%
day 14: 33%
day 16: 0%
When could hCG could be detected?
day20
prolactin
PRL inhibiting hormone is dopamine while all other hypothalmic releasing inhibitory hormones are peptides
PRL release is primarily under negative control and other hormones are under positive control
What is the major change in an endocrine regulatory sytem that causes the onset of puberty?
decreasing sensitiviy of gonadostat
What percent drop in ejaculate volume would be expected following vasectomy?
5%
What is the biomechanical mechanism of erection?
NO stimulates guanylcylcase -> increases cGMP causes relaxation of s muscles and increases blood flow through the arterioles. TypeV phosphodiesteroes hydrolyzes cGMP and reverses the relaxation. Viagra inhibits typeV PDE
Type 1 DM
diagnosis: autoimmune assay for glutamic acid decarboxylase, insulin and IA 2 transmembrane tyrosine phosphatase
twin concordance
Type 2 DM
diagnosis: >200mg/dL blood glucose after 75g glucose load
