week 3-tissue mineralization Flashcards
pathologic mineralization is due to
deposition of Ca salts in tissue
what does increased levels of Ca in cells cause
devastating results and sometimes irreversible cell injury
what is dystrophic mineralization
Ca deposition due to dysregulation at local level
what is metastatic mineralization
Ca deposition due to systemic dysregulation
animals with dystrophic calcification have _____ blood levels of Ca
normal
animals with metastatic mineralization have _____ levels of Ca
high
high levels of Ca
hypercalcemia
gross appearance:
tissue is white to tan and feels gritty
histologic appearance:
H&E stain: granular, deeply basophilic material
Von Kossa stain: brown-black
in dystrophic mineralization, how is Ca deposited?
cells that are necrotic/undergoing necrosis cannot regulate cystolic Ca levels and Ca is deposited
where is Ca normally absorbed
through the gut
where is Ca normally excreted
through the kidneys
In between absorption and excretion, normally, Ca _______
moves in between body compartments
the bone acts
as a storage depot
what happens when blood Ca is high
parafollicular cells inc secretion of calcitonin and parathyroid glands reduce PTH secretion
Ca is deposited
what does calcitonin do?
stimulates osteoblasts to remove Ca from blood and deposit it as bone
what does PTH do?
cause Ca mobilization from bone
also inhibits Ca loss via urine
also stimulates kidneys to make calcitriol
what happens when blood Ca is low
calcitonin secretion dec.
PTH secretion inc.
Ca liberated from bone
what does calcitriol do
increases intestinal absorption of Ca and mobilization from bone
what does vit D when metabolized
produces active metabolites such as calcidiol
what does calcidiol do?
acts on kidney to upregulate calcitriol
5 main mechanisms of hypercalcemia
- primary hyperparathyroidism
- hypercalcemia of malignancy
- vit D toxicosis
- renal failure
- bone destruction
what is primary hyperparathyroidism
functional neoplasms of the parathroid glands secreted inc. PTH and are not downregulated by normal control mechanisms
-cause hypercalcemia
what is hypercalcemia of malignancy
-non parathyroid neoplasms secrete PTHrp which mimick actions of PTH but bypass normal pathways that regulate PTH secretion
-leads to hypercalcemia
what is vit D toxicity
-due to increased amounts of vit D (ingested or metabolites or endogenous production of these metabolites)
-hypercalcemia and metastatic mineralization can be evidence of severe granulomatous inflamm
renal failure causes
retention of phosphates which results in imbalance of Ca and P which may induce parathyroid glands to secrete inc PTH
(secondary hyperparathyroidism)
what is bone destruction the result of
primary or metastatic neoplasia that destroys bone
common sites of metastatic mineral deposition:
-kidney
-parietal pleura
-pulmonary interstitium
-great vessels/left atrium
-gastric mucosa
-tongue
