calcium homeostasis

Question 1

what is hydroxyapatite?

Answer 1

minerals deposited on osteoid

Question 2

where are osteoclasts derived from?

Answer 2

haematopoietic stem cells

Question 3

where are osteoblasts derived from?

Answer 3

mesenchymal stem cells

Question 4

where are osteocytes derived from?

Answer 4

osteoblasts that become surrounded with calcified matrix

Question 5

what cell expressed RANKL?

Answer 5

osteoblasts

Question 6

what hormones favour bone resorption?

Answer 6

1. parathyroid hormone
2. cortisol
3. thyroid hormones (suppress TSH which has bone protective function)
4. 1,25-dihydroxyvitamin D (calcitriol)

Question 7

what hormones favour bone formation?

Answer 7

insulin, IGF-1, growth hormone, oestrogen, testoterone, calcitonin

Question 8

what does OPG do?

Answer 8

inhibit bone resorption by binding to RANKL

Question 9

which enzyme does parathyroid hormone stimulate in the vitamin D activation pathway?

Answer 9

1-alpha-hydroxylase

Question 10

which hormones increase plasma calcium levels?

Answer 10

PTH and 1,25-dihydroxyvitamin D (calcitriol)

Question 11

which hormone counteracts PTH?

Answer 11

calcitonin

Question 12

where is calcitonin secreted from?

Answer 12

parafollicular cells of thyroid gland

Question 13

where are parathyroid glands derived from?

Answer 13

pharyngeal pouches