Bone remodeling Flashcards
What are the functions of calcium?
Nervous excitability of RMP
Muscle contraction
Forms crystalline structure of bones and teeth
Secondary messenger for surface receptors
NTs at synapses
Blood clotting
What are the functions of phosphate?
Protein synthesis, cellular reproduction
Buffer
Hexose phosphate and creatine phosphate
Intermediary of metabolism
Energy transfer
What results from phosphate depletion?
Skeletal muscle weakness
Cardiac and respiratory muscle dysfunction
Loss of RBC membrane integrity
Abnormal bone formation
What enzymes are found in osteoclasts?
Collagenase and acid phosphatase
Where are receptors of PTH located in bone?
Osteoblasts and osteocytes
What are three general actions PTH has on bone?
Immediate
Intermediate
Delayed
What is the immediate action of PTH on bone?
Bone resorption leads to calcium entering ECF
What is the intermediate action of PTH on bone?
Increase in acid phosphate secretion, carbonic anhydrase enzyme, and lactic acid accumulation decrease pH which increases bone resorption
What is the delayed action of PTH on bone and when does it take place?
Activate osteoclasts and form new osteoclasts
After 12 hours
What is produced when PTH stimulates osteoblasts?
Increases RANK-L expression which increases osteoclast activity
Inhibits secretion of OPG
What is the role of OPG?
Competitively binds to RANK-L receptors on osteoclasts, decreasing resorption
What three things regulate plasma calcium and phosphate levels?
PTH
Calcitonin
Vit D3
What is the role of calcitonin?
Reduces calcium reuptake in kidneys and stimulates bone ossification
What is the role of glucocorticoids in bone remodeling?
Lower plasma calcium by inhibiting osteoclast formation and activity
What can be related to excessive calcium?
Over absorption from GI
Increase bone resorption
Hypercalcemia
Hypercalciuria
Renal stones
Deposition of calcium in soft tissues
