Bone Structure and Types
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Questions and Answers

What is the characteristic of collagen fibers in mature lamellar bone?

  • Randomly arranged in matrix
  • Disorganized arrangement
  • Parallel layers resulting in strong mature bone (correct)
  • Perpendicular to the bone surface

    • What is the primary function of woven bone?

  • To regulate bone marrow function
  • To provide structural support in mature bone
  • To produce osteoid
  • To facilitate rapid bone formation during fracture repair (correct)

    • What is the term for the functional unit of lamellar bone?

  • Lacunae
  • Canaliculi
  • Osteon (correct)
  • Haversian canal

    • What is the primary location of woven bone formation?

    <p>Sites of rapid bone formation</p> Signup and view all the answers

    What is the process by which woven bone is remodeled into lamellar bone?

    <p>Bone remodeling</p> Signup and view all the answers

    What is the characteristic of trabecular bone in bird bones?

    <p>Soft and rarefied</p> Signup and view all the answers

    What is the role of osteoid in bone formation?

    <p>To form the matrix of mature bone</p> Signup and view all the answers

    What is the term for the channels that connect lacunae in osteons?

    <p>Canaliculi</p> Signup and view all the answers

    What is the primary component of osteoid, making up approximately 90%?

    <p>Type I collagen</p> Signup and view all the answers

    What is the role of parathyroid hormone (PTH) in bone metabolism?

    <p>Promotes bone resorption</p> Signup and view all the answers

    What is the function of osteoclasts in bone remodeling?

    <p>To remove mineralized bone</p> Signup and view all the answers

    Which of the following hormones inhibits bone resorption?

    <p>Calcitonin</p> Signup and view all the answers

    What is the role of osteoblasts in bone remodeling?

    <p>To form osteoid</p> Signup and view all the answers

    What is the composition of hydroxyapatite, the inorganic component of bone?

    <p>Ca10(PO4)6(OH)2</p> Signup and view all the answers

    Which of the following is involved in the mineralization of osteoid?

    <p>Osteonectin</p> Signup and view all the answers

    What is the origin of stem cells that give rise to osteoclasts?

    <p>Bone marrow monocyte origin</p> Signup and view all the answers

    What is the primary function of osteoblasts in bone tissue?

    <p>To produce osteoid and initiate its mineralization</p> Signup and view all the answers

    What is the term for the thin channels running between lacunae in the Haversian system?

    <p>Osteonic canals</p> Signup and view all the answers

    What is the purpose of Howship's lacunae in bone remodeling?

    <p>To facilitate acid demineralization of bone matrix</p> Signup and view all the answers

    What is the origin of osteoclasts?

    <p>Monocytic origin</p> Signup and view all the answers

    What is the term for the canal that runs through the center of an osteon?

    <p>Haversian canal</p> Signup and view all the answers

    What is the role of parathyroid hormone (PTH) in bone remodeling?

    <p>To stimulate bone resorption by osteoclasts</p> Signup and view all the answers

    What is the composition of cortical bone?

    <p>Lamellar bone</p> Signup and view all the answers

    What is the location of osteons in mature bone?

    <p>Cortex of bones</p> Signup and view all the answers

    What is the function of osteonectin and osteocalcin in bone development?

    <p>They adsorb to type I collagen and bind Ca2+</p> Signup and view all the answers

    What occurs if osteoid fails to mineralize?

    <p>Rickets and osteomalacia develop</p> Signup and view all the answers

    Which type of ossification occurs in flat bones of the skull and pelvis?

    <p>Intramembranous ossification</p> Signup and view all the answers

    What precedes endochondral ossification?

    <p>Hyaline cartilage precursors</p> Signup and view all the answers

    What is the function of the physis?

    <p>Regulates bone growth in length</p> Signup and view all the answers

    What is the term for the growth plate at the ends of bones?

    <p>Physis</p> Signup and view all the answers

    What is the term for the shaft of a long bone?

    <p>Diaphysis</p> Signup and view all the answers

    What is the term for the region of bone tissue that regulates bone growth in width?

    <p>Periosteum</p> Signup and view all the answers

    What is the primary function of osteoblasts during bone formation?

    <p>To produce and deposit osteoid on top of cartilage spicules</p> Signup and view all the answers

    What is the type of bone that forms through the process of endochondral bone formation?

    <p>Cancellous bone</p> Signup and view all the answers

    What is the main difference between osteoid and bone tissue?

    <p>Osteoid is soft and unmineralized, while bone tissue is hard and mineralized</p> Signup and view all the answers

    What is the direction of blood flow in the cortex of young animals?

    <p>Centrifugally, from the endosteal surface to the periosteal surface</p> Signup and view all the answers

    What is the term for the process of bone tissue replacement and reshaping?

    <p>Bone remodeling</p> Signup and view all the answers

    What is the primary function of the metaphyseal arteries?

    <p>To supply blood to the cortex</p> Signup and view all the answers

    What is the term for the mature, organized bone tissue that forms through the process of bone remodeling?

    <p>Lamellar bone</p> Signup and view all the answers

    What is the primary function of the bone marrow?

    <p>To produce blood cells and platelets</p> Signup and view all the answers

    Study Notes

    Bone Structure

    • Mature lamellar bone is hard and strong, with collagen fibers arranged in parallel layers, while woven bone is soft and weak, with disorganized collagen fibers
    • Lamellar bone is formed slowly and is present in trabeculae and cortical bone, while woven bone is produced quickly and is present at sites of rapid bone formation (e.g. fracture repair, inflammation, neoplasia)

    Osteon and Haversian System

    • Osteon is the functional unit of lamellar bone, consisting of circles of bone around a central canal (Haversian canal) and interstitial bone between the circles
    • Haversian canal is seen at the center of each osteon, with Volkmann's canals running in bone and connecting Haversian canals

    Bone Cells

    • Osteoblasts produce osteoid (the organic component of bone matrix) and initiate its mineralization, and can become osteocytes
    • Osteocytes reside in lacunae surrounded by mineralized matrix, with long filopods to increase their cell area
    • Osteoclasts are responsible for bone resorption, residing in shallow pits (Howship's lacunae) and releasing acid hydrolases for extracellular digestion

    Regulation of Bone Metabolism

    • Parathyroid hormone (PTH) stimulates bone resorption and promotes calcium absorption
    • 1,25-dihydroxyvitamin D3 is required for normal bone growth and mineralization, and also stimulates bone resorption
    • Calcitonin inhibits bone resorption
    • Glucocorticoids inhibit bone formation and stimulate resorption
    • Estrogen inhibits bone resorption

    Bone Composition

    • Osteoid (organic component) contains type I collagen, osteonectin, osteocalcin, proteoglycans, and growth factors
    • Hydroxyapatite [Ca10(PO4)6(OH)2] is the inorganic component of bone

    Bone Development

    • Intramembranous ossification occurs in flat bones of the skull and pelvis, and on all periosteal surfaces throughout life, responsible for growth in width
    • Endochondral ossification occurs in most bones, preceded by hyaline cartilage, responsible for growth in length

    Bone Blood Supply

    • Blood enters the marrow cavity of bones through nutrient, metaphyseal, and epiphyseal arteries
    • In young animals, the cortex is supplied mainly from the endosteal surface and exits via periosteal veins
    • With age, the cortex becomes increasingly dependent on periosteal arteries

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    Description

    This quiz covers the different types of bone structures, including mature lamellar bone and woven bone, and their characteristics under polarized light.

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