Endocrine Flashcards
what hormones do the anterior pituitary secrete? (also called adenohypophysis)
FSH LSH ACTH TSH Prolactin GH Melantropin
What hormone does the posterior (neurohypophysis)?
Vasopressin
Antidiuretic hormone
ADH
oxytocin
What are the parts of the pancreas?
Islets of Langerhans (alpha, beta)
Alpha= gulcagon
B= insulin
Gamma= somatostatin
What are the steps of insulin?
pre-pro insulin to proinsulin to insulin
Briefly describe the mechanism of insulin?
Binds to insulin receptors on the cell
Induces glucose uptake
Gene transcription
Does insulin cross the placenta?
No, but glucose does
Which are insulin dependent transporters?
GLUT 4 (adipose tissue) striated muscle
Which one are insulin -dependent transporters?
GLUT 1: RBC (brain, cornea)
GLUT 2: liver, kidney, small intestine
GLUT 3: brain, placenta
GLUT 5: fructose
What does glucagon do? What cells secrete it?
1) Made by alpha cells of the pancrease
2) Catabolic effects (glycogenesis, gluconeogenesis)
3) Lipolysis and ketone production
4) Secreted in response to hypoglycemia
5) Inhibited by insulin, hyperglycemia, and somatostatin
What are the hypothalamic-pituitary hormones?
1) CRH
2) Dopamine
3) GHRH
4) GnRH
5) Prolactin
6) Somatostatin
7) TRH
What does CRH do?
Increases ACTH, MSH, B endorphin
Decreased in chronic exogenous steroid use.
What does dopamine do?
Decrease prolactin
Increase TSH
Dopamine antagonists can cause galactorrhea due to hyperprolactinemia
What does GnRH?
Increased FSH, LH
Suprreses hyperprolactinemia
What does prolactin do?
Decrease GnRH
If have a prolactinemia —>amenorrhea, osteoporosis, hypogonadism, galactorrhea
What does somatostatin do?
Decrease GH, TSH
Used to treat acromegalu
What does TRH do?
Increased TSH, prolactin
Function of prolactin?
Stimulates milk production in the breast
Inhibits ovulation in females and spermatogenesis in males
Too much prolactin leads to decreased libido
How does prolactin inhibit it’s own production?
prolactin is secreted by anterior pituary
(inhibited by dopamine)
Prolactin will inhibit its own secretion by STIMULATING dopamine
How are prolactinemia treated?
Bromocriptine (dopamine agnosit) inhibits the secretion of prolactin
What are side effects of dopamine antagonists? what are common dopamine antagnoists?
1)antipyschotics
They will stimulate the production of prolactin
What does the growth hormone Somatotropin do?
Secreted by the anterior pituitary
Stimulates linear growth and muscle mass
Secretion is increased during exercise or deep sleep
Released when pulse of GHRH
Excess GH leads to gigantism or acromegaly
What are the hormones responsible for appetite regulation?
1) Grehlin
2) Leptin
3) Endocannabinoids
What does Ghrelin do?
What increases production?
1) Stimulate hunger and GH release
2) Sleep deprivation and Prader-Willi can increase production
What does leptin do?
Satiety hormone
Produced by adipose tissue
Can be produced by sleep deprivation or starvation
What do endocannabinoids do?
Receptors in the hypothalamus
Increase the appetite (munchies)
Where is anti-diuretic hormone made?
What is the function?
1) Posterior pituitary
2) Regulates osmolarity and blood pressure
What happens to ADH level in diabetes insipidus?
ADH is decreased in central diabetes insipidus
However it can be increased in nephorgenic DI
How is the antidiuretic hormone regulated?
Osmoreceptors in hypothalamus (hypovolemia)
What is the source, regulation, and effects of cortisol?
1) Adrenal zona fasciculata Function: 1) Increase blood pressure 2) Increase insulin resistence 3) Increase glucogenesis 4) decrease fibroblast activity 5) Inhibit WBC adhemsion 6) Reduce esinophils 7) decrease bone formation
Regulation:
CRH (hypothalamus) stimulates ACTH release from the pituitary
Chronic stress will prolong secretion
What are the three forms of ionized calciumÉ
Ionized (45%)
Bound to albumin (40%)
Bound to anions (15%)
What happens to calcium when you change the ph?
Increase in pH will increase the affinity of calcium
Can lead to hypocalcemia (pain, parethsis, carpopedal spasm)
What is source, function, and regulation of vitamin D (cholecalciferol)?
1) Exposure of the skin to the sun
2) eating from fish and plants
3) Both are converted to 25-OH in liver and to 1,25 in the kidney
Function:increased absoption of dietery Calcium and phosphate
Regulation: Increased PTH will lead to decreased calcium and phosphate
The 1,25 (OH) will inhibit it’s own production
What medical conditions are caused by deficiency of vitamin D?
1) Ricketts in kids
2) Osteomalacia in adults
3) Malabsorption (Decrease sunlight)
What is the source, function, and regulation of the parathyroid hormone?
1) Produced by chief cells
2) Increase bone absortpiont of Ca 2+
3) Increase absorption of Ca in the kidneys
4) Decrease resoprtion of phosphate
What is the source, function, regulation of calcitonin?
1) Parafollicular cells of the thyroid
2) Decrease bone resorption of the Ca
3) Increase serum Ca
Calcitonin opposes action of PTH
What are the source, function of the thyroid hormone?
Source: follicles of the thyroid
Function: Bone growth Increased B receptors of the heart Increased basal metabolic rate Increase glycogenolysis Increase glucogenesis Increase lipolysis
Regulation:
Through the TRH (hypothalamus) stimulates the follicular cells
Can also be stimulated by TSI (thyroid stimulating immunoglobulin) in Graves disease
What is the difference between the T3 and T4? What does the thyroid binding globulin do?
T4 is the major thyroid product, and converted to T3 in the periphereal tissue
The thyroxine binding globulin binds to T3/T4 in the blood, so only free hormone is active
What is the Wolff-Chaikoff effect?
Excess iodine inhibits the thyroid peroxidase (decrease iodine organification) and decrease the T3 and T4 production
What is the cycle of thyroid release?
Hypothalamus releases the TRH—–acts on the anterior pituitary—-releases the TSH—–causes the thyroid follicular cells to release the thyroid hormone
What are the signalling pathways of endocrine hormones?
1) cAMP
2) cGMP
3) IP3
4) Intracellular receptors:progesterone, estrogen, testosterone, cortisol, aldosterone
5) Receptor tyrosine kinas: Insulin, IGF-1. FGF, PDFG, EGF
5) Non receptor tyrosine kinase: IL-2, IL-6, IFN
What is the effect of sex hormone binding globulin on men/women?
In men, increase in SHBG lowers the free testosterone causing gynecomastia
In women decrease in SHBG increases the free testosterone causing hirutism
What is the etiology of cushing?
Increased in cortisol
Cause: exogenous use (results in decreased ACTH, bilateral adrenal atrophy)
Primary adrenal adenoma
ACTH secreting adenoma
what are the findings associated with Cushing?
HTN Weight gain Moon farcies Abdominal Striae Truncal Obesity Buffalo hump Amenorrhea
what is the screening test of Cushings?
1) Increase free cortisol on 24 hour urinalysis
2) Increase midnight salivery cortisol
3) No suppression with overnight low-dose dexamthesone test
How to determine if it is ACTH-independent Cushings?
Measure ACTH
If ACTH suppressed, then have an ACTH-independent Cushing syndrome
(do MRI do confirm an adrenal tumor)
If the ACTH is elevated, then have ACTH dependent Cushing syndrome
The next step is to do a high dose, dexamethsone suppresion test OR CRH stimulation test
CRH
(Increase ACTH, and cortisol = Cushing disease)
No increase in ACTH means ectopic (ectopics don’t respond to stimulation, they are independent).
If adequate suppression (Cushing disease)
No suppression then have ectopic ACTH secretion
What is adrenal insufficiency?
Inability to generate glucocorticoids or mineral corticoids
Symptoms: weakness, fatigue, orthostatic hypotension, weight loss, GI disturbances, sugar or salt cravings
How is adrenal insufficiency diagnosed?
Measure serum electrolytes (morning and random cortisol)
What is primary adrenal insufficiency?
Low cortisol, high ACTH
Metrapone stimulation test: (blocks least step of cortisol synthesis), normal response is decreased in cortisol and compensatory increase in ACTH. In primary, the ACTH increases, but 11-deoxycortisol remains low.
what are the results of secondary adrenal insufficiency?
low cortisol, low ACTH (hypothalamic disease)
What is primary adrenal insufficiency?
Aldosterone and cortisol
Causes:
Hypotension (hyponatremic) hyperkalemia, metabolic acidosis
Acute: sudden onset (due to hemorrage) may present with acute adrenal crisis
Chronic: Addison’s disease: adrenal atrophy or destruction by disease
What is the waterhouse-friderichsen syndrome?
Primary adrenal insufficiency due to adrenal hemorrage associated with Neisseria
How to seperate primary, from secondary adrenal insufficiency?
Decrease pituitary ACTH production (no skin/mucosal hyperpigmentation) no hyperkalemia
What is tertiary adrenal insufficiency?
Seen in patients with exogenous use of steroids
Precipitated by abrupt withdrawl
Aldosterone synthesis unaffected
What is hyperaldosterone?
Increased secretion of aldosterone from the adrenal gland
Clinical features include hypertension and metabolic acidosis
What is primary hyperaldosterone?
Adrenal Adenoma (Conn Syndrome) Idopathic adrenal hyperplasia Inceased aldosterone Decreased renin
What is secondary hyperaldosterone?
Renovascular hypertension
Juxtaglomuler cell tumor
What are neuroendocrine tumors?
Neoplasms originating from the Kulchitsky and enterochromaffin-like cells
In the thyroid, medullary carcinoma
what are neuroblastoma tumors?
Most common tumor in children