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Anatomy & Physiology: Osseous Tissue and Skeletal System

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Terms in this set (21)

  • Five primary functions of the skeletal system

    Support, storage of minerals and lipids, blood cell production, protection, and leverage for movement.

  • Classification of bones by shape

    Sutural, irregular, short, flat, long, and sesamoid bones.

  • Characteristics of flat bones

    Thin with parallel surfaces; composed of spongy bone (diploë) between two layers of compact bone.

  • Structure of a long bone

    Consists of diaphysis (shaft), metaphysis (growth region), and epiphysis (ends), with compact bone surrounding spongy bone and a medullary cavity.

  • Bone matrix composition

    Two thirds mineral (calcium phosphate as hydroxyapatite) and one third collagen fibers.

  • Four types of bone cells

    Osteoprogenitor (stem cells), osteoblasts (bone-forming), osteocytes (mature bone cells), and osteoclasts (bone-resorbing).

  • Function of osteoblasts

    Secrete organic components of bone matrix (osteoid) and initiate calcification.

  • Function of osteocytes

    Maintain bone matrix and help repair damaged bone; reside in lacunae connected by canaliculi.

  • Function of osteoclasts

    Multinucleate cells that dissolve bone matrix by secreting acids and enzymes, releasing stored minerals.

  • Basic functional unit of compact bone

    Osteon, composed of concentric lamellae around a central (Haversian) canal containing blood vessels.

  • Role of canaliculi in bone

    Small canals that connect lacunae and allow exchange of nutrients and wastes between osteocytes and blood vessels.

  • Structure of spongy bone

    Network of trabeculae without osteons; spaces filled with red or yellow bone marrow.

  • Periosteum structure and function

    Outer membrane covering bone except at joints; has fibrous and cellular layers; provides blood supply and participates in growth and repair.

  • Endosteum location and function

    Lines inner surfaces of bone including medullary cavity; contains osteoblasts, osteoclasts, and progenitor cells; active in growth and repair.

  • Endochondral ossification process

    Bone replaces hyaline cartilage through stages: cartilage enlargement, calcification, blood vessel invasion, spongy bone formation, and remodeling.

  • Intramembranous ossification

    Bone develops directly from mesenchymal tissue; forms flat bones like mandible and clavicle.

  • Hormones affecting bone growth

    Growth hormone, thyroxine, estrogens, androgens stimulate osteoblasts; calcitonin and parathyroid hormone regulate calcium balance.

  • Parathyroid hormone (PTH) effects on calcium

    Increases blood calcium by stimulating osteoclasts, increasing intestinal absorption via calcitriol, and reducing kidney excretion.

  • Calcitonin effects on calcium

    Decreases blood calcium by inhibiting osteoclasts, reducing intestinal absorption, and increasing kidney excretion.

  • Steps in fracture repair

    1. Hematoma formation, 2. Callus formation, 3. Spongy bone formation, 4. Compact bone remodeling.

  • Effects of aging on bones

    Bone mass decreases (osteopenia), leading to osteoporosis; bones become thinner, weaker, and more fragile.