Parathyroid hormone (PTH) has what effect on the skeletal system?
Parathormone or parathyroid hormone influnces bony tissue to remain dynamic.
There are two types of cells in bones:
- osteoblasts which secrete bony matrix, which become inactive with time and are called osteocytes.
- osteoclasts which are macrophagic cells, which are able to remove the inactive osteocytes.
Activity of osteoclasts is influenced positively by parathormone.
By degrading the old bony tissue osteoclasts release calcium in blood. Thus parathormone increases serum calcium level.
On the other hand, parathormone increases excretion of phosphates through urine, thus serum phosthate level decreases.
There is hormone calcitonin which is antagonistic to parathormone, thus it keeps osteoclast activity under control.