Endocrine Path Quiz 3- part 3 Flashcards
parathyroid glands is controlled by the level of
free (ionized) calcium in bloodstream
decreased serum levels of free calcium stimulate the synthesis and secretion of
PTH
function of PTH
PTH tells kidneys to absorb more calcium from diet, and body to elaborate more of active Vitamin D
PTH and calcitonin act inversely, how?
PTH act to increase conc. of calcium in bloodstream
Calcitonin acts to decrease conc. of calcium
where is PTH made?
chief cells of parathyroid glands
where is calcitonin made?
parafollicular cells C cells
Sometimes these cells have a clear appearance due to large amounts of glycogen stored within the cell
Chief cells
most common cause of primary hyperparathyroidism?
adenoma
other causes of primary hyperparathyroid?
primary hyperplasia
parathyroid carcinoma
microscopic view of parathyroid adenoma
hypercellularity
well encapsulated
little fat
tendency towards follicular formation
microscopic view of normal parathyroid
prominent adipose tissue
most common cause of secondary hyperparathyroidism?
renal failure
Less phosphate excreted in urine, resulting in hyperphosphatemia. The elevated serum phosphate levels directly depress serum calcium levels and thereby stimulate parathyroid gland activity.
microscopic changes seen in secondary hyperparathyroidism
same as adenoma (primary hyperparathyroidism)
loss of adipose
hypercellularity
but NOT encapsulated
microscopic view of parathyroid carcinoma
bands of fibrous tissue between nests of neoplastic cells
malignancy related to hypercalcemia most commonly due to
stem cell capacity of some cancer to make ectopic hormone called PTHrP (Parathyroid hormone-related protein) (resembles PTH)
