Endocrinology Flashcards
Thyroid follicular cells arise from endoderm, mesoderm, or ectoderm?
Endoderm
The anterior pituitary (adenohypophysis) is derived from the oral endoderm, mesoderm, or ectoderm?
Oral ectoderm (Rathke pouch)
FLAT PeG
What substances are secreted from the anterior pituitary?
FSH
LH
ACTH
TSH
Prolactin
Growth hormone
What substances are secreted from the posterior pituitary?
ADH and oxytocin
Somatotropin is another name for what substance?
Growth hormone
The posterior pituitary is derived from neural endoderm, mesoderm, or ectoderm?
Neuroectoderm
GFR
What is the name of the 3 layers of the adrenal cortex?
Glomerulosa
Fasciculata
Reticularis
What hormone is produced by the zona glomerulosa?
Aldosterone (mineralocorticoids)
What hormone is produced by the zona fasciculata?
Cortisol (glucocorticoids)
the adrenal cortex is derived from the endoderm, mesoderm, or ectoderm?
Mesoderm
The adrenal medulla is derived from the endoderm, mesoderm, ectoderm, or neural crest?
Neural crest
Compare and contrast somatostatin vs somatotropin
Somatotropin (trop) is also called growth hormone. It is released from the anterior pituitary.
Somatostatin (statin) is released from the hypothalamus and the delta cells of the pancreas. Its function is to inhibit growth hormone and TSH release
Which substances are released from these pancreatic cells?
alpha
beta
delta
Alpha - glucagon
Beta - insulin
Delta - somatostatin (GH inhibitor)
Thyroid releasing hormone is released by the hypothalamus causing the release of what from the anterior pituitary?
TSH and prolactin
Prolactin release from the anterior pituitary is inhibited by what?
Dopamine
Prolactin release is decreased or increased by estrogen?
Increased.
Prolactin has a negative effect on what?
GnRH. This decreases FSH and LH
Exercise, sleep, and hypoglycemia will decrease or increase release of somatrotropin?
Increase
Method of action of octreotide
It is a somatostatin analog.
It will act on somatrotropes in the anterior pituitary to decrease release of somatrotropin (Growth hormone)
Central diabetes insipidus has a high or low level of ADH
Low
ADH is high or low in nephrogenic diabetes
Normal or high
ADH acts on what parts of the kidney
Distal convoluted tubule and collecting ducts
What is the key function of ADH?
To regulate serum osmolality and volume
Low volume = increase ADH
High osmolality = increase ADH
What is the effects of dopamine agonists (bromocriptine and cabergoline) on prolactin release?
Dopamine agonists will decrease the release of prolactin.
Useful in prolactinomas
What is the effect of dopamine antagonists (antipsychotics, metoclopramide) on prolactin release?
Dopamine antagonists will increase prolactin release.
5’ deiodinase function
It converts T4 to T3 in the peripheral tissues
What 3 substances inhibit peripheral conversion from T4 to T3?
Glucocorticoids
Beta blockers
PTU
Thyroid peroxidase function
Organification of iodine, coupling of MIT and DIT in the follicular lumen of the thyroid
PTU inhibits what 2 enzymes?
Both Thyroid peroxidase (in the lumen) and 5’ deiodinase (in the periphery)
Thyroid peroxidase is inhibited by?
PTU and methimazole
Is T3 or T4 more active?
T3
T3 acts on what receptors of the heart?
B-adrenergic (B1). It increases cardiac output, heart rate, SV, and contractility
Thyroxine-binding globulin is increased in what states?
Pregnancy
Oral contraception use (increased estrogen)
This will cause a decrease in free, active T3, T4
Thyroxine binding globulin is decreased in what states?
Nephrotic syndrome (lost in urine)
Steroid use
What is the source of parathyroid hormone?
Chief cells of the parathyroid
Result of increased PTH on phosphate absorption in the GI system and bone resorption?
Increased. Will increase the levels so that it can be excreted in the urine
Results of PTH on calcium reabsorption in the distal collecting tubule
Increased reabsorption
PTH works on what part of the kidney to increase vitamin D3 production via 1a-hydroxylase
proximal collecting tubule
Increased PTH increases which ligand on osteoblasts and osteocytes?
RANK-L
Function of RANK-L
RANK-L is expressed on osteoblasts and osteocytes. It binds to RANK receptor on osteoclasts which activates the osteoclasts. THis leads to bone resorption
PTHrP is commonly increased in which cancers?
Squamous cell carcinoma of lung, renal cell carcinoma
Decreased serum magnesium increases or decreases PTH secretion?
Increases
How is calcium carried in the plasma?
Mostly Ionized/free
40% bound to albumin
15% bound to anions
Does changes in albumin concentration alter PTH secretion?
No. The biggest regulator is plasma pH
In low pH states, there is more H+ which binds to albumin. How does this effect free calcium levels?
Less calcium can bind to albumin = more free calcium. This will decrease PTH secretion
In high pH states, there is less H+ to bind to albumin. How does this effect calcium concentration?
Decreases free calcium concentration since the calcium can now bind to albumin. This will increase PTH secretion
Does calcitonin increases or decrease bone resorption?
Decrease. The function of calcitonin is to decrease Calcium levels. Bone resorption would increase calcium levels.
How does calcitonin decrease bone resorption?
Inhibits osteoclasts
Glucagon is inhibited by which 4 substances?
Insulin, amylin, somatostatin, hyperglycemia
Preproinsulin is synthesized in what part of pancreatic B cells?
the Rough ER
After cleavage of preproinsulin, proinsulin is found where?
In secretory vesicles
After cleavage of proinsulin, which 2 products released from the secretory vesicles?
Insulin and C-peptide
What kind of receptors does insulin bind to?
Tyrosine kinase
What is the effect of insulin on sodium in the kidneys?
Increases sodium retention
What is the effect of insulin on potassium and amino acids?
Increases the cellular uptake of potassium and amino acids
Which insulin-independent transporter is found on the liver and beta islet cells?
GLUT 2 (bidirectional)
GLUT4 is the glucose transporter found on adipose tissue and striated muscle. Is it insulin dependent or independent?
GLUT4 brings glucose inside of adipose tissue and striated muscle. It is dependent on insulin.
An influx of what ion causes insulin release from pancreatic beta cells?
Calcium (voltage gated)
ATP generated from glycolysis in pancreatic beta cells closes which channel?
Potassium efflux channel
All of the adrenal enzyme deficiencies are inherited how?
Autosomal recessive
If the adrenal deficiency starts with 1, it causes what?
Hypertension
What is the effect of adrenal insufficiency?
An increase in ACTH secretion
Which hormone is made in the supraoptic nucleus of the hypothalamus?
ADH
Which hormone is made in the paraventricular nucleus of the hypothalamus?
Oxytocin
Pituitary tumors result in what kind of visual deficit?
Bitemporal hemanopia
Bitemporal hemanopia resulting from a pituitary tumor is due to compression of what structure?
Optic chiasm
What is the effect of ethanol on ADH secretion?
Decrease. When you drink, you urinate a lot = low ADH
Low blood pressure/Low ANP will increase or decrease ADH secretion
Increase. The ADH will cause reabsorption of water = increase blood volume
Elevated TRH would have what effect on prolactin levels.
Increase. High TRH = High TSH = Stimulate Prolactin release
Diabetes insipidus results in dilute or concentrated urine?
Dilute. Low ADH = not conserving water = more water in the urine = dilute
Causes of nephrogenic diabetes insipidus
Polycystic kidney disease
ADH or aquaporin receptor mutation
The kidney is unable to respond to ADH –> dilute urine
Why does diabetes insipidus cause increased thirst?
ADH is used to decrease serum osmolality. The high serum osmolality causes polydipsia.
Urine osmolality results with water deprivation test in central diabetes insipidus and nephrogenic DI
Unchanged. The urine will still be dilute because ADH is still not working on the kidneys to dilute the urine
Urine osmolality results after exogenous ADH administration in patients with central DI
Increase
Urine osmolality results in patients with diabetic DI after given ADH
No change in urine osmolality. The kidney is still not able to concentrate the urine
Serum levels of sodium in SIADH
Low sodium
Adrenal insufficiency would have what effects on CRH and ACTH?
Increase
Somatostatin downregulates what substances?
Growth hormone
Glucagon
Insulin
gastrin
VIP
MEN1 - 3 P
MEN1 is associated with tumors in which areas?
Pituitary
Pancreas
Parathyroid
MEN1 is due to mutation of what gene?
MEN1 gene which codes for menin. It is on chromosome 11
MEN2A and 2B are associated with a mutation in what gene?
RET gene
Which MEN condition is associated with Marfanoid body type?
Type 2B
Method of action of sulfonylureas and metglitinides
Closes efflux potassium channels in pancreatic beta cells leading to depolarization. This causes calcium to flow in and insulin is released
Graves Disease is due to autoantibodies to what receptor?
Autoantibodies to the TSH receptor. This stimulates the TSH receptor on the thyroid gland leading to increased T3/T4
Which class of diabetic medications has a long onset of action and can cause weight gain?
Thiazolidinedione. PPAR agonist. Example) Rosiglitazone
Upregulates GLUT4 transporters
Method of action of SGLT2 (flozin) medications
Blocks reabsorption of glucose in the proximal convoluted tubule
Method of action of GLP-1 agonists (exenatide, liraglutide)
Increases insulin secretion from the pancreas
Decrease glucagon levels
Slows gastric emptying
Karyotype 47 XXY is what syndrome?
Klinefelter Syndrome
In Klinefelter syndrome (XXY) the patient is phenotypically male or female?
Male. Developmental delay such as testicular hypoplasia and gynecomastia
Methimazole method of action
Inhibits thyroid peroxidase
Drug of choice for non-pregnant patients
Type 1 Diabetes is strongly associated with which HLA subtype?
HLA - DR4
What enzyme converts excess glucose to sorbitol?
Aldolase B
Mechanism of action of bile acid resins
Bind bile acids int he GI tract,inhibiting enterohepatic circulation.
This increases uptake of LDL from circulation
Which medication can cause a decrease of LDL but increase in triglycerides?
Bile acid resins (cholestyramine)
Method of action of ezetimibe
Inhibit intestinal absorpitoin of cholesterol
Which medication is first line for hypertriglyceridemia
Fibrates. It inhibits hepatic production of triglycerides
Side effect of PTU
Hepatotoxicity
Which medication can cause a reduced awareness of hypoglycemia
Nonselective beta blockers - propanolol
The calm down the effects of epinephrine
Sympathetic stimulation of a2 receptors on pancreatic beta cells causes what effect on insulin release?
Inhibits insulin secretion
sympathetic stimulation of b2 receptors causes what effect on pacreatic beta cells (insulin release)
Increases insulin release
What hormone is increased during menopause?
FSH due to resistant follicles
What is increased in 17a hydroxylase deficiency?
Starts with 1 = salty = aldosterone
Glucocoricoids and androgens are low
The impaired synthesis of androgens in 17a hydroxylase deficiency leads to what symptoms?
Genetic males appear phenotypically female but have a blind vagina.
There is lack of pubetery/secondary sexual characteristics in both boys and girls
11 hydroxylase deficiency leads to an increase in what?
deoxycorticosterone (weak aldosterone) and androgens
Method of action of tamsulosin?
alpha adrenergic antagonist –> smooth muscle relaxation
Method of action of spironolactone
Aldosterone receptor antagonist but also inhibits androgen receptors
Mechanism of action of -flozin medications
Glucose “flows in” the urine.
SGLT-2 inhibitor which decreases the reabsorption of sodium and glucose inthe proximal tubule
How do steroids cause osteoporosis
Inhibit differentiation of osteoblast precursors
Increase expression of RANK/RANKL
Decrease calcium reabsorption
Function of cholecystokinin
Increase gallbladder contraction, sphincter of Oddi relaxation
Pancreatic secretion
Side effects of methimazole and PTU
Severe neutropenia –> oropharyngeal ulcers, fever
Effect of estrogen on bone density
estrogen is protective
estrogen decreases RANK expression on osteoclasts
