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Anatomy & Physiology: Bones & Skeletal Tissues

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Terms in this set (29)

  • Functions of the skeletal system
    Support, protection, anchorage for muscles, mineral storage (calcium & phosphate), blood cell formation (hematopoiesis), and triglyceride storage in yellow marrow.
  • Three types of cartilage
    Hyaline (most abundant, flexible support), Elastic (more elastic fibers, flexible), and Fibrocartilage (thick collagen fibers, withstands pressure).
  • Hyaline cartilage characteristics
    Amorphous but firm matrix with collagen fibers; chondrocytes in lacunae; supports and reinforces; found in embryonic skeleton, articular cartilage, costal cartilage, nose, trachea, and larynx.
  • Elastic cartilage characteristics
    Similar to hyaline but with more elastic fibers; maintains shape with flexibility; located in external ear (pinna) and epiglottis.
  • Fibrocartilage characteristics
    Matrix less firm than hyaline with thick collagen fibers; tensile strength absorbs compressive shock; found in intervertebral discs, pubic symphysis, and knee menisci.
  • Classification of bones by shape
    Long bones (longer than wide), short bones (cube-shaped), flat bones (thin, flattened), and irregular bones (complex shapes).
  • Long bone anatomy: diaphysis
    Tubular shaft forming the long axis; thick collar of compact bone surrounding the medullary cavity filled with yellow bone marrow in adults.
  • Long bone anatomy: epiphyses
    Bone ends with outer compact bone and inner spongy bone; covered with articular (hyaline) cartilage; separated from diaphysis by epiphyseal line.
  • Periosteum layers
    Outer fibrous layer of dense irregular connective tissue; inner osteogenic layer containing osteoprogenitor cells, osteoblasts, and osteoclasts.
  • Endosteum
    Membrane lining internal bone surfaces including trabeculae and canals; contains osteoprogenitor cells, osteoblasts, and osteoclasts.
  • Bone marrow types and locations
    Red marrow in infants fills medullary cavity and spongy bone; in adults, red marrow is in trabecular cavities of spongy bone in proximal epiphyses and diploë of flat bones; yellow marrow stores fat.
  • Four main bone cell types
    Osteoprogenitor cells (stem cells), osteoblasts (bone matrix secretion), osteocytes (maintain matrix), osteoclasts (bone resorption).
  • Osteon structure
    Structural unit of compact bone; concentric lamellae of bone matrix with collagen fibers alternating directions; central canal contains blood vessels and nerves.
  • Canals in compact bone
    Central canal runs through osteon center; perforating canals connect central canals to medullary cavity; lacunae house osteocytes connected by canaliculi.
  • Spongy bone structure
    Contains trabeculae aligned with stress lines; irregular lamellae and osteocytes connected by canaliculi; lacks osteons.
  • Chemical composition of bone
    Organic components: bone cells and osteoid (ground substance and collagen fibers); inorganic components: mineral salts, mainly hydroxyapatite (65%).
  • Endochondral ossification
    Bone develops by replacing hyaline cartilage; forms most bones below the skull except clavicles.
  • Intramembranous ossification
    Bone develops from fibrous connective tissue membranes; forms flat bones of the skull and clavicles.
  • Zones of long bone growth in length
    Proliferation zone, hypertrophic zone, calcification zone, and ossification zone in the epiphyseal plate.
  • Appositional growth
    Bone growth in thickness; osteoblasts add bone matrix on external surface, osteoclasts remove bone on endosteal surface.
  • Bone remodeling
    Continuous process of bone resorption by osteoclasts and deposition by osteoblasts; about 5-10% of bone replaced yearly.
  • Role of osteoclasts in bone resorption
    Multinucleated cells that break down bone matrix by secreting acid and enzymes; create grooves and release minerals into bloodstream.
  • Role of osteoblasts in bone deposition
    Secrete osteoid which calcifies; proteins bind calcium triggering mineralization and formation of hydroxyapatite crystals.
  • Hormones regulating calcium homeostasis
    Parathyroid hormone (PTH) and calcitriol regulate blood calcium levels via bone remodeling.
  • Wolff's law
    Bone grows or remodels in response to mechanical stress and gravitational forces.
  • Fracture classifications by bone end position
    Non-displaced (bone ends retain normal position) and displaced (bone ends out of normal alignment).
  • Fracture classifications by completeness
    Complete (bone broken through) and incomplete (partial break).
  • Fracture classifications by skin penetration
    Open (compound) fractures penetrate skin; closed (simple) fractures do not.
  • Common bone disorders
    Osteomalacia (soft bones), rickets (childhood osteomalacia), osteoporosis (bone resorption > deposition), Paget's disease (excessive disorganized bone remodeling), osteosarcoma (malignant bone tumor).