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Bone Formation, Growth, Remodeling, and Fracture Repair

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Terms in this set (20)

  • What is Osteogenesis?

    Osteogenesis is the process of bone formation, including the development, growth, remodeling, and repair of bones.

  • What are the two main types of Osteogenesis?

    Endochondral and Intramembranous osteogenesis are the two main types of bone formation.

  • Describe Endochondral Osteogenesis.

    Bone forms by replacing a cartilage model; it is responsible for forming most bones, especially long bones.

  • Describe Intramembranous Osteogenesis.

    Bone develops directly from mesenchymal tissue without a cartilage stage, mainly forming flat bones like the skull.

  • Name the primary bone cells involved in bone formation and remodeling.

    Osteoblasts build bone, osteocytes maintain bone, and osteoclasts break down bone.

  • What is the role of osteoblasts?

    Osteoblasts synthesize and secrete the bone matrix and initiate mineralization.

  • What is the function of osteocytes?

    Osteocytes are mature bone cells that maintain the bone matrix and communicate mechanical stress.

  • What do osteoclasts do?

    Osteoclasts resorb bone by breaking down the mineral matrix during remodeling and repair.

  • What stimulates bone remodeling?

    Mechanical stress, calcium ion levels, and hormonal signals stimulate bone remodeling in either formation or resorption.

  • How does plasma calcium regulation affect bone remodeling?

    Low plasma calcium triggers bone resorption to release calcium; high calcium promotes bone formation to store calcium.

  • Which hormones regulate plasma calcium and bone remodeling?

    Parathyroid hormone (PTH) increases calcium by stimulating osteoclasts; calcitonin lowers calcium by inhibiting osteoclasts.

  • What is the first step in fracture repair?

    Formation of a hematoma at the fracture site to stop bleeding and provide a foundation for healing.

  • What happens during the fibrocartilaginous callus formation?

    Fibroblasts and chondroblasts produce a soft callus of collagen and cartilage to bridge the fracture gap.

  • Describe the bony callus formation stage.

    Osteoblasts replace the soft callus with a hard bony callus of spongy bone, stabilizing the fracture.

  • What occurs during bone remodeling after fracture repair?

    The bony callus is remodeled into compact bone, restoring the bone's original shape and strength.

  • How does mechanical stress influence bone remodeling?

    Increased mechanical stress stimulates osteoblast activity to strengthen bone; lack of stress leads to bone resorption.

  • What is the role of osteocytes in sensing mechanical stress?

    Osteocytes detect mechanical load and signal osteoblasts and osteoclasts to adjust bone remodeling accordingly.

  • Why is calcium important for bone health?

    Calcium is essential for bone mineralization, strength, and serves as a critical ion in many physiological processes.

  • What triggers osteoclast activation during low plasma calcium?

    Parathyroid hormone (PTH) stimulates osteoclasts to resorb bone and release calcium into the blood.

  • How does calcitonin affect bone cells?

    Calcitonin inhibits osteoclast activity, reducing bone resorption and lowering blood calcium levels.