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Anatomy & Physiology: Bones and Bone Tissue

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Termini in questo insieme (27)

  • Main organs of the skeletal system
    The main organs are bones, which include osseous tissue, dense regular and irregular collagenous connective tissue, and bone marrow.
  • Functions of the skeletal system
    • Protection of organs
    • Mineral storage and acid-base homeostasis
    • Blood cell formation (hematopoiesis)
    • Fat storage
    • Movement
    • Support
  • Classification of bones by shape
    • Long bones: longer than wide (e.g., femur)
    • Short bones: cube-shaped (e.g., carpals)
    • Flat bones: thin and broad (e.g., ribs)
    • Irregular bones: complex shapes (e.g., vertebrae)
    • Sesamoid bones: within tendons (e.g., patella)
  • Structure of a long bone
    Includes periosteum, perforating fibers, diaphysis (shaft), epiphyses (ends), articular cartilage, marrow cavity, compact bone, spongy bone, endosteum, and epiphyseal lines.
  • Difference between compact and spongy bone
    Compact bone is dense and resists compression and twisting; spongy bone is porous with trabeculae that resist forces from multiple directions and house bone marrow.
  • Components of bone extracellular matrix
    Bone matrix is 65% inorganic minerals (mainly hydroxyapatite) and 35% organic matrix (osteoid) including collagen fibers and proteins.
  • Role of hydroxyapatite crystals in bone
    Hydroxyapatite crystals \(\mathrm{Ca}_{10}(\mathrm{PO}_4)_6(\mathrm{OH})_2\) provide hardness and resistance to compression.
  • Function of collagen fibers in bone
    Collagen fibers form cross-links that help bone resist torsion and tensile forces and align with hydroxyapatite to enhance hardness.
  • Functions of osteoblasts
    Osteoblasts build bone by secreting organic matrix and assisting in inorganic matrix formation during bone deposition.
  • Functions of osteocytes
    Osteocytes maintain bone matrix and reside in lacunae; they are metabolically less active but regulate local bone maintenance.
  • Functions of osteoclasts
    Osteoclasts break down bone by resorbing bone matrix, secreting acids and enzymes to dissolve inorganic and organic components.
  • Structure of an osteon
    An osteon consists of concentric lamellae, a central canal with blood vessels and nerves, lacunae with osteocytes, and canaliculi connecting lacunae.
  • Role of canaliculi in bone
    Canaliculi are small channels that allow osteocytes to communicate and share nutrients through cytoplasmic extensions.
  • Difference between compact and spongy bone histology
    Compact bone is organized into osteons; spongy bone has trabeculae with lamellae and lacunae but no osteons, receiving blood from marrow vessels.
  • Intramembranous ossification
    Bone forms directly from mesenchymal membrane, producing flat bones like skull and clavicles via primary ossification centers.
  • Endochondral ossification
    Bone forms from a hyaline cartilage model, replacing cartilage with bone; forms most bones below the head except clavicles.
  • Zones of the epiphyseal plate involved in longitudinal growth
    • Zone of proliferation: chondrocytes divide
    • Zone of hypertrophy: chondrocytes enlarge
    • Zone of calcification: cartilage matrix calcifies
    • Zone of ossification: bone replaces calcified cartilage
  • Process of appositional growth
    Osteoblasts in the periosteum add new bone layers on the surface, increasing bone width by forming new circumferential lamellae.
  • Effects of growth hormone on bone growth
    Growth hormone increases chondrocyte division in epiphyseal plate, stimulates osteogenic cells, and promotes appositional growth by osteoblasts.
  • Effects of testosterone on bone growth
    Testosterone increases appositional growth, accelerates mitosis in epiphyseal plate causing growth spurts, and speeds epiphyseal plate closure.
  • Effects of estrogen on bone growth
    Estrogen increases longitudinal growth, inhibits osteoclasts, causes growth spurts, and accelerates epiphyseal plate closure faster than testosterone.
  • Bone remodeling process
    Continuous cycle of bone deposition by osteoblasts and resorption by osteoclasts to maintain calcium homeostasis and adapt to stress.
  • Response of bone to mechanical stress
    Bone deposition increases with compression and tension; bone resorption occurs with continuous pressure.
  • Role of parathyroid hormone (PTH) in calcium homeostasis
    PTH increases blood calcium by stimulating osteoclasts to resorb bone, enhancing gut absorption, and reducing urinary calcium loss.
  • Role of calcitonin in calcium homeostasis
    Calcitonin lowers blood calcium by promoting bone deposition, pulling calcium into bone matrix; active mainly during growth.
  • Stages of fracture healing
    • Hematoma formation
    • Soft callus formation by fibroblasts and chondroblasts
    • Bone callus formation by osteoblasts
    • Bone remodeling replacing primary bone with secondary bone
  • Difference between simple and compound fractures
    Simple fractures do not break the skin; compound fractures involve skin and tissue damage around the fracture.