First Pass Miss Exam 3 Flashcards
What other hormone do chromophobes release?
ACTH
What releasing hormones does the arcuate nucleus control?
acidophil releasing hormones (GHRH, PIH = dopamin)+ basophils gonadotrophs only
What releasing hormones does the paraventricular nucleus release?
all the rest: CRH and TRH
What type of receptor is the oxytocin receptor?
GalphaQ -> increases calcium concentrations for duct contraction
What are the three components of the efferent end of the sucking reflex?
- Inhibit dopamine release to increase prolactin
2;. Stimulation production and release of oxytocin by posterior pituitary - Inhibition of GnRH release, preventing further pregnancy
What are the two types of vasopressin receptors?
V1a - Galphaq to increase calcium for vasoconstriction
V2 - in kidney collecting duct increase cAMP to move aquaporin-2 to the membrane
Why doesn’t desmopressin significantly raise blood pressure while increasing blood volume?
Does not bind V1a receptor for vasoconstriction
What is TBG?
Thyroxin binding globulin - carries both T3/T4, but has 3x the affinity for T4
What causes Graves’ disease?
Antibodies overstimulate follicular cells “thyroid stimulating IGs” - activate TSHR
Goiter can result from increased iodine requirement
What cells produce parathyroid hormone and what type of hormone is it?
Peptide hormone produced via chief cells
What are the short and longterm effects of parathyroid hormone?
Short - stimulate bone deposition by osteoblasts (good osteoporosis treatment)
Long - stimulate osteoblasts to secrete M-CSF, IL-6, and RANK-L to recruit osteoclasts
How does osteoprotegrin work?
It’s a decoy receptor for RANK-L, thus preventing some osteoclast recruitment.
How does the PTH receptor work?
High extracellular calcium stimulates GalphaQ to increase intracellular calcium concentration, which actually BLOCKS PTH secretion.
What is the function of PTH in kidney outside of excretion of phosphate + reabsorption of calcium?
Activates 1alpha-hydroxylase enzyme so that 25-OH-D3 (primary circulating form of D3, made in liver) can be converted to 1,25-OH-D3 = Calcitriol.
What are the two effects of calcitriol?
- Primary effect - increase number of calcium channel + gut resorption of calcium
- Secondary effect - increase bone breakdown to increase plasma calcium concentration.
Primary effect trumps the secondary effect -> bone will end up being net built.
What stimulates calcitonin secretion?
Primarily GI hormones -> control of blood calcium after a meal, but also high blood calcium in general.
Synthesized as procalcitonin before being cleaved.
What is the function of calcitonin?
Inhibits osteoclasts, decreasing both phosphate and Ca+2. It’s super important during pregnancy when cortisol is high and bone tends to be resorbed, prevents bone breakdown.
What causes Rickets?
Vitamin D deficiency in children -> bowed legs due to less mineralization
What causes osteomalacia?
Vitamin D deficiency in adults -> bone weakness and fracture susceptibility
What is the main risk factor for osteoporosis?
Menopause, since estrogen stimulates bone mineralization.
What releases somatostatin? What is its effect?
Periventricular nucleus -> GalphaI to decrease cAMP and prevent GH release from somatotrophs, the most numerous cell type in the gland. Also inhibits TSH release from thyrotropes
Stimulated by IGF-1
Where is GHRH released and what is its effect?
Arcuate nucleus -> GalphaS to increase cAMP and stimulate GH release
Inhibited by IGF-1
When is GH released?
Diurnal pattern -> largest peak 1 hour after onset of sleep, in Stage 3 deep sleep
What stimulates GH release?
Since it has some prodiabetic effects, it is released in response to energy deficiency: hypoglycemia, fasting, exercise, low concentration of FFA, elevated glucagon.
Also: Elevated sex hormones + ingestion of protein rich meal
What suppresses GH release?
GH, IGF-1, cortisol (as in psychosocial short stature), HYPERGLYCEMIA (since it has pro-diabetic effects)
What type of receptor is the growth hormone receptor?
JAK/STAT = janus kinase, induces signal transducer and activation of transcription.
In the receptor tyrosine kinase family
What are the acute effects of growth hormone?
prodiabetic - gluconeogenesis, lipolysis, decreased glucose uptake in muscle
What are the longterm / chronic effects of growth hormone
IGF-1 -> increases macromolecule synthesis, organ size, bone growth, and anabolic effects in general
What hormone is oxytocin related to?
7/9 of the same amino acids as vasopressin
What family is somatotropin in?
Same family as human prolactin