14: Hormones of Calcium Metabolism- Schmidt Flashcards
make bone
calcium chloride + sodium phosphate = calcium-phoshpate
pseudogout =
calciumphosphate crystals in the joint when the ions reach critical concentrations
what enzyme activities need calcium directly? indirectly?
citric acid cycle and glycogen degradation
indirectly - calmodullin
calcium is essential for …
blood coagulation and muscle contraction
required also for the stability of bone
in serum, about ______% calcium is free and ____% bound to prtns or small molecules
50/50
only free calcium is physiologically active
goal of calcium pool regulation
keep calcium concentration in ECF constant
calcium and______ are regulated inversely
phosphate
ex: mobilization of bone calcium is accompained by increase in phosphate excretion. also high phosphate intake leads to increased calcium excretion
stimulates calcium uptake in the gut
calcitriol
stimulates resorption of bone calcium into the serum and stimulates synthesis of calcitriol in kidney
PTH
stimulates calcium excretion by the kidney
calcitionin
“calcistat”
the calcium stasis system
drawn out in notes with effects of PTH and CT
PTH is synthesized…
in the chief cells of the parathyroid glands
calcitonin is synthesize in….
the thyroid glands
CT and PTH are both
peptide hormones
binding of PTH to receptors leads to activation of…
- the cAMP/PKA pathway
- the phospholipase C/ Prtn Kinase C pathway
what are the actions of PTH in the kidney?
- increases resorption of Calcium in the distal tubule, the collecting duct and the ascending limb of the loop of Henle
- stimulaes phosphate excretion
- stimulates synthesis of calcitriol
effects of PTH in bone
stimulates the resorption f calcium by osteoclasts
calcitonin acts through…
g-prtns and signal via cAMP levels
physiological actions of calcitonin
bone - inhibits resorption of calcium
kidney - stimulates calcium excretion
calcitriol is synthesized from
cholesterol
so it is awater-insolluble steroid derivative
calcitriol synthesis involves skin, liver and kidney (in this order)
target organs of calcitriol
intestine
bone
kidney
stimulates the transcription of calcium binding prtns, calcium ATPase, facilitators of vesicle formation
low vitamin d levels or insufficient calcium intake
ricketts/osteomalacia
osteoid matrix and cartilage are formed, but not minearlized leading to soft, pliable bones
kidney disease leads to calcium loss in urine, insufficient calcitriol production
renal osteodystrophy
GH effects on calcium homeostasis
stimulates bone remodeling
glucocorticoids effects on calcium homeostasis
- reduce absorption from GI
- decrease calcium reabsorption
- inhibit bone formation
- stimulate PTH secretion
estrogen effects on calcium homeostasis
- increase calcium reabsorption from kidney
- inhibit PTH mediated bone resorption
