Bone Composition and Remodeling

Questions and Answers

Inhibiting osteoclasts and increasing osteoblast proliferation

Decreases bone resorption and increases bone formation

Reduced risk of breast cancer

Because it reduces the risk of breast cancer Signup and view all the answers

Stimulates osteoclasts Signup and view all the answers

Agonist in bone, stimulating osteoblasts Signup and view all the answers

Increased risk of venous thromboembolism Signup and view all the answers

Binding to RANKL Signup and view all the answers

To identify and manage any dental issues before treatment Signup and view all the answers

Slows bone loss Signup and view all the answers

Study Notes

Bone is composed of 25% organic matrix (osteoid, type 1 collagen fibers, cells: osteoblasts, osteoclasts, osteocytes) and 75% inorganic matrix (crystalline calcium and phosphate salts, primarily hydroxyapatite)
Bone plays a crucial role in maintaining overall body calcium homeostasis
99% of total body calcium is stored in bone as crystalline hydroxyapatite

Bone remodeling is a continuous process regulated by hormones, mechanical factors, and cytokines
Osteoblasts (formation) and osteoclasts (resorption) are key cells involved in bone remodeling
Glucocorticoids, thyroid hormone, and estrogen have a greater impact on bone remodeling in cases of deficiency or excess
Parathyroid hormone (PTH) is the principal regulator of calcium homeostasis and balance
Vitamin D contributes to maintaining calcium balance

Osteoporosis is a bone disorder characterized by an imbalance between bone resorption and formation, leading to increased bone fragility and susceptibility to fracture
Parathyroid hormone (PTH) analogues are anabolic agents that increase bone formation
Antiresorptive agents, such as bisphosphonates, hormone replacement therapy (HRT), and selective estrogen receptor modulators (SERMs), slow down bone loss
RANKL antagonists and calcimimetic compounds, such as cinacalcet, are used to treat hyperparathyroidism

PTH acts to increase and maintain plasma calcium levels through direct and indirect effects on bone and kidney
PTH increases calcium reabsorption and promotes phosphate excretion in the kidney
PTH has anabolic and catabolic effects on bone, with anabolic effects increasing bone formation and catabolic effects increasing bone resorption
The anabolic window refers to the early bone formation events and increased bone mass seen with intermittent low-dose exposure to PTH

Teriparatide is a recombinant human parathyroid hormone (PTH 1-34) used to promote bone formation in severe osteoporosis
Bisphosphonates are bone anabolic agents that inhibit bone resorption by modifying osteoclast activity and increasing bone mass
There are two classes of bisphosphonates: non-nitrogen-containing bisphosphonates (NNBPs) and nitrogen-containing bisphosphonates (NBPs)
Examples of bisphosphonates include etidronate, alendronate, ibandronate, risedronate, and zoledronate

Hormone replacement therapy (HRT) and selective estrogen receptor modulators (SERMs) are antiresorptive agents that slow down bone loss
Raloxifene is a SERM that has tissue-selective effects, stimulating osteoblasts and inhibiting osteoclasts
Strontium ranelate is an alternative to bisphosphonates for the prevention of osteoporosis in postmenopausal women with increased risk of breast cancer

Questions and Answers