ESR[036]: Endocrine Control of Calcium Homeostasis Flashcards
Which types(s) of serum Ca 2+ is biologically active ??
Only free, ionized Ca 2 + is biologically active
……are the differentiated bone forming cells and secrete bone matrix on which Ca ++and PO4 precipitate.
Osteoblasts
Inorganic bone is composed of….. & organic matrix is composed primarily of……
hydroxyapatite , collagen
Alkaline phosphatase and osteocalcin plasma levels are indicators of…….. activity
osteoblast
Requirements of mineralization ?
• Requires adequate Calcium and phosphate
• Dependent on Vitamin D
• Alkaline phosphatase and osteocalcin play roles in bone formation
Two groups of people with - and
+ calcium balances ?
• In growing children: intestinal absorption > renal excretion (+ve balance) ~10mmol/day »_space; ↑calcium content by 400 mg/day
• In post-menopausal women, output (from bone)»_space; input»_space; negative Ca 2 + balance
The blood supply to the parathyroid glands is from the……. arteries
thyroid
Structure of Parathyroid Hormone ?
is an 84 amino acid single chain protein, released from th chief cell in the parathyroid glands.
Parathyroid Hormone secretion is regulated via vitamin …
vitamin D
Other substances that affect PTH release ?
And how ?
The main PTH actions ?
Tissue distribution of Calcium Sensing Receptor ?
How does the parathyroid sense ECF Ca2+concentration changes ?
Elaborate
How does vitamin D affect PTH ?
1,25-(OH)2 -D inhibits PTH gene expression, providing another level of feedback control of PTH.
Effects of PO4 on PTH regulation ?
Despite close connection between Ca 2+and PO4, no direct control of PTH is exerted by phosphate levels.
Types of Hypoparathyroidism ?
1) Iatrogenic: accidental removal of parathyroid glands during thyroid surgery
2) Idiopathic: failure of parathyroid hormone secretion of unknown cause»_space; Low circulating PTH, hypocalcaemia and hyperphosphataemia
3) Pseudohypoparathyroidism: tissue resistance to PTH action due to mutation in PTH receptor or decreased receptor expression
Pseudohypoparathyroidism pathogenesis ?
main indications of Parathyroidectomy ?
therapy- resistant hypercalcaemia and/or hyperphosphatemia.
Defects in the neural crest-derived APUD cells give rise to……., whereas increased proliferation of those APUD cells not derived from the neural crest give rise to……
multiple endocrine neoplasia (MEN)2 ,, MEN1
Explain steps of Vitamin D synthethis
effect of vit D on transcription ?
Factors (other than calcium) that influence 1α-hydroxylase activity ?
How does vitamin D3 circulate ?
Effect of Calcitriol on 24-hydroxylase and 1αhydroxylase ?
• Calcitriol induces 24-hydroxylase and represses 1αhydroxylase
Effect of PTH on 1αhydroxylase ?
And what’s it’s significance ?
Effect of Calcitonin , cortisol, oestrogen and prolactin on 1α-hydroxylase activity ?
Calcitonin suppresses 1α-hydroxylase, whereas growth h cortisol, oestrogen and prolactin increase its activity
