Endocrine physiology review, mnemonics Flashcards
Hypercalcemia symptoms:
“stones, bones, groans, and psychiatric overtones”
- stones–renal
- Bones–bone pain
- Groans–weakness, constipation
- psychiatric overontes–depression
What blocks the Na-I transporter in the thyroid? (2)
- Thiocyanate (cyanide)
- can be side effect of nitroprusside for HTN emergency - Perchlorate
- byproduct in rocket propellants. can be in contaminated drinking water.
Both cause decreased I uptake, so hypothyroidism
why does oral glucose induce a stronger insulin response than injected glucose?
Oral glucose also stimulates the secretion of GIP (glucose-dependent insulinotropic peptide) from the GI tract
Why is there no lactation during pregnancy, even though prolactin levels are high?
Estrogen and progesterone down-regulate prolactin receptors. After parturition, both E and P decrease, releasing inhibition.
Anterior pituitary:
- secretes what
- what do Ant Pit basophils secrete?
FLAT PeG:
FSH, LH, ACTH, TSH, Prolactin, GnRH
B-FLAT:
FSH, LH, ACTH, TSH
How does chronic renal failure affect Ca levels?
2 mechanisms:
- Decreased resorption of Ca
- decreased 1 OHlation of 25 Vit D, so decreased Ca intake.
- Note: in secondary hyperparathyroidism, Ca levels may be normal instead of low because the PTH has compensated for the low Ca
Why is there hyperkalemia in T1 DM?
Insulin promotes K uptake into cells (protects body from transient hyperkalemia after a meal).
No insulin means hyperkalemia
starvation effect on thyroid hormones/metabolism
Starvation inhibits 5’ iodinase in TH target tissues, except in brain. 5’ iodinase is required to convert T4 to T3, so this effect is beneficial in reducing basal metabolic rate during starvation.
17A OHlase deficiency:
-are aldosterone levels increased or decreased?
- Aldo is decreased, although it would seem to increase at first thought.
- The excess mineralocorticoid symptoms act on the RAAS to reduce Aldosterone synthase. (HTN reduces renin, reduces Angio II, reduces Aldo synthase. Hypokalemia directly reduces Aldo synthase)
- So, excess 11-DOC and Corticosterone are formed, which cause the mineralocorticoid symptoms.
Calcitonin
-function
“calcitonin TONES down Ca levels”
-decrease Ca blood levels by decreasing bone resorption
ADH:
2 major stimulators. which one overrides the other in case of conflict?
- increased osmolarity (person deprived of water)
- hypovolemia (eg bleeding)
Blood volume overrides. Eg: person has hypervolemia but increased osmolarrity–no ADH
Eg: person has hypovolemia but decreased osmolarity–yes ADH secretion
what happens to thryoid hormone levels during pregnancy and why?
High estrogen during pregnancy inhibits liver’s breakdown of TBG (thyroid binding globulin). Therefore, more T4/T3 is bound to TBG and free T4/T3 goes down.
In response, the thryroid gland produces more TBG in response to low free T4/T3. Final result: Increased TBG and normal free T4/T3 levels.
Pt is ‘clinically euthyroid’ meaning thyroid function is normal despite increased TBG levels.
Ant vs Post pituitary:
-how are the connections from hypothalamus different?
Ant: hormone, by blod
post: neural
Which organs uptake glucose independent of insulin’s effect?
‘BRICK L’
Brain, RBCs, Intestine, Cornea, Kidney, Liver
Signaling pathways of endocrine hormones:
steroid receptor
‘VETTT CAP’
VitD, Estrogen, Testosterone, T3, T4
Cortisol, Aldosterone, Progesterone
Anterior and posterior pituitary:
-derived from what tissues?
- ant–oral ectoderm (rathke’s pouch)
- post–neuroectoderm
Adrenal cortex and medulla:
divided in what parts, and what do they secrete?
“GFR,” “Salt, sugar, and sex”
Zona glomerulosa–Aldosterone
fasciculata–Cortisol, also androgens
reticularis–androgens
Medulla–catecholamines
dexamethasone suppression test:
- what is it used for
- how does it work
- Used in pts with hypercortisolism to dx primary or secondary.
- If there is an ACTH-secreting tumor in the AP, low lose of dexamethasone will have no effect, but high dose will lower ACTH and therefore cortisol level. (tumor tissue is less sensitive to glucocorticoid negative feedback).
- If there is a cortisol-secreting tumor in the adrenal gland, no amount of dexamethasone will affect cortisol level (tumor has no negative feedback from glucocorticoid)
Signaling pathways of endocrine hormones:
cAMP
“FLAT ChAMP”
FSH, LH, ACTH, TSH
CRH, hCG, ADH, MSH, PTH,
calcitonin, GHRH, glucagon
How do these affect calcium blood levels?
- changes in plasma protein concentration
- changes in anion concentration
- acid-base abnormalities
Remember, 40% of total blood Ca is bound to proteins, mainly albumin. 60% is free, ionized Ca.
- decreased albumin will decrease total blood Ca. Free Ca levels are usu not increased b/c this process happens slowly
- Increased PO4 will complex with free Ca, lowering free Ca.
- H+ competes with Ca for space on albumin, so in acidosis, free Ca increases. in alkalosis, free Ca decreases.
(thus, in acute respiratory alkalosis, free Ca decreases and you see signs of hypocalcemia)
How does cortisol inhibit inflamm/immune response? (5 mechs)
Inflammatory, Immune responses–decreases.
- inhibits production of LTs, prostaglandins.
- inhibits leukocyte adhesion–neutrophilia
- blocks histamine release from mast cells
- reduces eosinophils
- blocks IL-2 production
Posterior pituitary:
-secretes what?
ADH, Oxytocin
T3 functions
“4 B’s”
- Brain maturation
- Bone growth
- Beta-adrenergic effects
- Basal metabolic rate, increases
Signaling pathways of endocrine hormones:
IP3
“GOAT HAG”
GnRH, Oxytocin, ADH, TRH
Histamine, Angio II, Gastin
