Parathyroid gland Flashcards
How does the skeleton help to buffer serum calcium levels?
Through the release and uptake of calcium phosphate
What are the three functions of parathyroid hormone?
1) Stimulate bone resorption 2) Stimulates calcium reabsorption and phosphate excretion in the kidneys 3) Stimulates hydroxylation of VitD3 to its active form calcitrol
What are the two effects of calcitrol?
Increased absorption of Ca2+ at the kidneys and GI and increased bone resorption
PTH has a serum binding protein. True or false?
False
PTH is continuously synthesised but where is it stored?
PTH is not stored
Which cells is PTH secreted from?
Chief cells in the parathyroid gland
Where is the PTH-CA2+ receptor found?
On chief cells and in the kidney tubules
During high Ca2+, PTH degradation is …….
Stimulated
High serum phosphate, ….. PTH secretion
Stimulates
High serum magnesium, ….. PTH secretion
Inhibits
What are the target organs of PTH? (2)
Bone and kidney
Osteoclasts are stimulated by PTH. What is the role of osteoclasts?
They break down bone
Ca2+ is taken up in the small intestine. In which parts of the small intestine?
The duodenum and the jejenum
To activate vitamin D, how many hydroxylation reactions are required?
Two
What enzyme catalyses the formation of calcitrol from VitD3?
1a-hydroxylase