Bone disorders

Question 1

Cells of mature bones

Answer 1

Osteoblasts- build bone

Osteoclasts- resorb bone

Question 2

3 main hormones involved in calcium and phosphate regulation

Answer 2

Vitamin D- increase plasma calcium levels

Parathyroid hormone- increase plasma calcium levels

Calcitonin- Decrease plasma calcium levels

Question 3

Parathyroid Hormone (PTH)

Answer 3

Released from parathyroid gland inside thyroid gland

decrease in calcium level in blood, stimulates release, aims to increase calcium ions in the plasma

Increase osteoclast activity is the direct result of PTH levels increasing

Question 4

Calcitonin

Answer 4

Increase in calcium, stimulates thyroid gland to release calcitonin

Aims to decrease calcium plasma levels

Question 5

PTH affects on the bone

Answer 5

Osteoblasts have a PTH receptor on them, PTH will bind to this receptor, causing:

• osteoblasts will proliferate
• stimulate the expression of rank ligand on osteoblast
• will stimulate osteoblast to stop making osteoprotegerin

Osteoclasts have a rank receptor, when when there is a rank ligand expressed on an osteoblast, they will combine

the rank complex causes:
- causes osteoclasts to proliferate and differentiate

when this occurs:
- pre-osteoclasts become active osteoclasts and multinucleated
- when osteoclasts come into contact with the bone, acid will be release, damaging the bone and causing bone resorption:
– causing the minerals to be released (calcium and phosphate) into the blood