Bone Biology and Composition
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Questions and Answers

What is the primary function of Type I collagen in bone tissue?

  • Conferring strength and resilience to bone
  • Providing tensile strength to bone (correct)
  • Regulating bone remodeling cycles
  • Aiding in the synthesis of bone-specific proteins
  • What is the approximate percentage of bone protein mass accounted for by noncollagenous proteins?

  • 80-90%
  • 50-60%
  • 10-15% (correct)
  • 20-30%
  • What is the role of versican in bone formation?

  • Inhibiting bone resorption
  • Delineating areas destined to become bone (correct)
  • Regulating osteoblast activity
  • Promoting bone deposition
  • What is the purpose of osteoblasts in bone tissue?

    <p>Synthesizing and secreting bone-specific proteins</p> Signup and view all the answers

    What is the function of chondroitin sulfate proteoglycans, decorin, and biglycan in bone tissue?

    <p>Influencing cellular proliferation and differentiation</p> Signup and view all the answers

    What is the characteristic of albumin and PDGF that allows them to be bound to hydroxyapatite in bone tissue?

    <p>Negatively charged</p> Signup and view all the answers

    What is the primary function of alkaline phosphatase in bone mineralization?

    <p>To hydrolyze PPi, promoting mineralization</p> Signup and view all the answers

    What is the role of osteocytes in bone remodeling?

    <p>To regulate the recruitment of osteoclasts to areas of microdamage</p> Signup and view all the answers

    What is the primary function of RANKL in osteoclastogenesis?

    <p>To promote the formation of osteoclasts</p> Signup and view all the answers

    What is the role of osteopontin and bone sialoprotein in bone mineralization?

    <p>To provide an initial scaffold for mineralization</p> Signup and view all the answers

    What is the role of fibroblast growth factor 23 (FGF23) in bone metabolism?

    <p>To regulate phosphate metabolism</p> Signup and view all the answers

    What is the role of macrophage colony stimulating factor-1 (M-CSF) in osteoclastogenesis?

    <p>To potentiate the effects of RANKL</p> Signup and view all the answers

    What post-translational modification enhances calcium binding in proteins such as osteocalcin and Matrix Gla-protein?

    <p>γ-carboxylation</p> Signup and view all the answers

    What is the function of osteonectin in bone tissue?

    <p>Regulation of bone mineralization</p> Signup and view all the answers

    What is the annual rate of bone renewal in compact bone in healthy adults?

    <p>4% of compact bone</p> Signup and view all the answers

    What is the primary function of RANKL in osteoblasts?

    <p>Stimulation of osteoclastic bone resorption</p> Signup and view all the answers

    What is the role of alkaline phosphatase in bone tissue?

    <p>Generation of inorganic phosphate ions for bone mineralization</p> Signup and view all the answers

    What is the function of osteocalcin in bone tissue?

    <p>Regulation of bone mineralization</p> Signup and view all the answers

    What is the primary source of inorganic phosphate ions for bone mineralization?

    <p>Intestinal absorption of phosphate</p> Signup and view all the answers

    What is the role of the RANK-RANKL-OPG system in bone remodeling?

    <p>Regulation of osteoclastic bone resorption</p> Signup and view all the answers

    What is the function of decorin and biglycan in bone tissue?

    <p>Chondroitin sulfate proteoglycans</p> Signup and view all the answers

    What is the primary function of osteoblasts in bone remodeling?

    <p>Synthesis and maintenance of bone matrix</p> Signup and view all the answers

    What is the primary function of osteoprotegerin in the context of osteoclastogenesis?

    <p>To act as a decoy receptor for RANKL</p> Signup and view all the answers

    What is the primary role of carbonic anhydrase in the process of bone resorption?

    <p>To produce H+ ions</p> Signup and view all the answers

    What is the result of partial uncoupling or imbalance between bone resorption and formation?

    <p>Metabolic bone diseases</p> Signup and view all the answers

    What is the primary function of chondrocytes in cartilage?

    <p>To produce and degrade collagen and proteoglycans</p> Signup and view all the answers

    What is the effect of TGF-β and IGF-I on cartilage?

    <p>They exert an anabolic effect on cartilage</p> Signup and view all the answers

    What is the result of an autoimmune attack on articular proteins in cartilage?

    <p>Altered balance between cartilage degradation and formation</p> Signup and view all the answers

    What is the primary function of RANKL in the context of osteoclastogenesis?

    <p>To stimulate osteoclast activity</p> Signup and view all the answers

    What is the primary function of the ruffled border in osteoclasts?

    <p>To produce acid and enzymes</p> Signup and view all the answers

    What is the result of a mineralization defect in bone?

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

    What is the effect of PTH, 1,25(OH)2D, PGE2, and IL-11 on osteoclasts?

    <p>They stimulate osteoclast activity</p> Signup and view all the answers

    What is the main component of bone tissue that confers strength and resilience?

    <p>Crystalline hydroxyapatite</p> Signup and view all the answers

    What is the function of osteoblasts in bone tissue?

    <p>Synthesis and secretion of organic compounds</p> Signup and view all the answers

    Which of the following proteins is not synthesized by osteoblasts, but arrives in bone via the circulation?

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

    What is the characteristic of hydroxyapatite that allows it to bind to albumin and PDGF?

    <p>Positively charged</p> Signup and view all the answers

    What is the function of versican in the early stages of bone formation?

    <p>Delineating areas destined to become bone</p> Signup and view all the answers

    What is the percentage of bone protein mass accounted for by collagen?

    <p>85-90%</p> Signup and view all the answers

    What is the primary function of acidic phosphoproteins in bone mineralization?

    <p>To provide a scaffold for nucleation</p> Signup and view all the answers

    What is the role of osteocytes in bone remodeling?

    <p>To maintain the bone matrix</p> Signup and view all the answers

    What is the function of RANKL in osteoclastogenesis?

    <p>To induce osteoclastogenesis</p> Signup and view all the answers

    What is the role of macrophage colony stimulating factor-1 (M-CSF) in osteoclastogenesis?

    <p>To potentiate the effects of RANKL</p> Signup and view all the answers

    What is the effect of osteocytic apoptosis on bone remodeling?

    <p>It initiates bone remodeling</p> Signup and view all the answers

    What is the function of sclerostin produced by osteocytes?

    <p>To inhibit osteoblast function</p> Signup and view all the answers

    What is the primary mechanism by which osteoblasts regulate osteoclastic bone resorption?

    <p>Through the production of OPG</p> Signup and view all the answers

    What is the function of the enzyme alkaline phosphatase in bone tissue?

    <p>To generate inorganic phosphate ions needed for bone mineralization</p> Signup and view all the answers

    What is the primary function of osteocalcin in bone tissue?

    <p>To bind to calcium ions in bone</p> Signup and view all the answers

    What is the result of an imbalance between RANKL and OPG in bone tissue?

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

    What is the function of chondroitin sulfate proteoglycans in bone tissue?

    <p>To regulate bone matrix formation</p> Signup and view all the answers

    What is the primary function of osteonectin in bone tissue?

    <p>To regulate bone matrix formation and mineralization</p> Signup and view all the answers

    What is the post-translational modification that enhances calcium binding in proteins such as osteocalcin and Matrix Gla-protein?

    <p>γ-carboxylation</p> Signup and view all the answers

    What is the annual rate of bone renewal in trabecular bone in healthy adults?

    <p>20% per year</p> Signup and view all the answers

    What is the function of the RANK-RANKL-OPG system in bone tissue?

    <p>To regulate osteoclast formation and activity</p> Signup and view all the answers

    What is the function of alkaline phosphatase in osteoblasts?

    <p>To generate inorganic phosphate ions needed for bone mineralization</p> Signup and view all the answers

    What is the function of osteoprotegerin in osteoclastogenesis?

    <p>To act as a decoy receptor for RANKL and inhibit osteoclastogenesis</p> Signup and view all the answers

    What is the result of decreased bone mass due to an imbalance between bone resorption and formation?

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

    What is the function of carbonic anhydrase in bone resorption?

    <p>To produce H+ ions</p> Signup and view all the answers

    What is the role of CSF-1 in osteoclastogenesis?

    <p>To stimulate the production of osteoclasts</p> Signup and view all the answers

    What is the characteristic of the sealed space between the ruffled border and the bone surface?

    <p>It is acidic</p> Signup and view all the answers

    What is the function of integrin-mediated binding in osteoclastogenesis?

    <p>To attach osteoclasts to the bone surface</p> Signup and view all the answers

    What is the result of a mineralization defect in bone?

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

    What is the function of proteoglycans in cartilage?

    <p>To provide compressibility and deformability</p> Signup and view all the answers

    What is the effect of PTH, 1,25(OH)2D, PGE2, and IL-11 on osteoclasts?

    <p>They stimulate the activity of osteoclasts</p> Signup and view all the answers

    What is the role of calcitonin in bone resorption?

    <p>It inhibits the activity of osteoclasts</p> Signup and view all the answers

    What is the main component of bone tissue that provides tensile strength?

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

    Which of the following ions is NOT typically found in bone tissue?

    <p>K+</p> Signup and view all the answers

    What is the function of osteoblasts in bone tissue?

    <p>To synthesize and secrete organic compounds of bone</p> Signup and view all the answers

    What is the primary function of bone sialoprotein?

    <p>To influence cellular proliferation and differentiation</p> Signup and view all the answers

    Which of the following proteins is typically bound to hydroxyapatite in bone tissue?

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

    What is the primary function of crystalline hydroxyapatite in bone tissue?

    <p>To confers strength and resilience to bone tissue</p> Signup and view all the answers

    What is the role of Pi/PPi in bone mineralization?

    <p>It is critical for mineralization</p> Signup and view all the answers

    What is the function of osteopontin in bone mineralization?

    <p>It provides an initial scaffold for mineralization</p> Signup and view all the answers

    What is the result of osteocytic apoptosis in bone tissue?

    <p>It releases apoptotic bodies that express RANKL</p> Signup and view all the answers

    What is the role of RANKL in osteoclast development?

    <p>It promotes osteoclastogenesis</p> Signup and view all the answers

    What is the function of sclerostin produced by osteocytes?

    <p>It is an endogenous inhibitor of osteoblast differentiation and function</p> Signup and view all the answers

    What is the function of fibroblast growth factor 23 (FGF23) in bone metabolism?

    <p>It is involved in the regulation of phosphate metabolism</p> Signup and view all the answers

    What is the function of RANKL shed from the osteoblast surface?

    <p>To confer osteoclastogenic activity distant from the cell of origin</p> Signup and view all the answers

    What is the role of osteoprotegerin in osteoclastogenesis?

    <p>To act as a decoy receptor for RANKL</p> Signup and view all the answers

    What is the effect of PTH, 1,25(OH)2D, PGE2, and IL-11 on osteoclasts?

    <p>To increase osteoclast activity</p> Signup and view all the answers

    What is the function of calcitonin in bone resorption?

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

    What is the result of a mineralization defect in bone?

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

    What is the function of chondrocytes in cartilage?

    <p>To produce and degrade collagen and proteoglycans</p> Signup and view all the answers

    What is the effect of TGF-β and IGF-I on cartilage?

    <p>To stimulate cartilage growth</p> Signup and view all the answers

    What is the result of an autoimmune attack on articular proteins in cartilage?

    <p>Loss of cartilage organization</p> Signup and view all the answers

    What is the function of carbonic anhydrase in the process of bone resorption?

    <p>To produce H+ and pump H+ into the resorption area</p> Signup and view all the answers

    What is the result of partial uncoupling or imbalance between bone resorption and formation?

    <p>Metabolic bone diseases</p> Signup and view all the answers

    Which of the following proteins is modified by the post-translational γ-carboxylation?

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

    What is the function of osteoblasts in bone tissue?

    <p>Synthesize and maintain bone matrix</p> Signup and view all the answers

    What is the role of RANKL in bone remodeling?

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

    What is the function of alkaline phosphatase in bone mineralization?

    <p>Generate inorganic phosphate ions</p> Signup and view all the answers

    What is the approximate percentage of bone tissue that is renewed annually in healthy adults?

    <p>4% of compact bone and 20% of trabecular bone</p> Signup and view all the answers

    What is the role of osteonectin in bone tissue?

    <p>May regulate both cellular activity and matrix mineralization</p> Signup and view all the answers

    What is the function of chondroitin sulfate proteoglycans in bone tissue?

    <p>May serve to promote attachment of bone cells to bone matrix</p> Signup and view all the answers

    What is the result of an imbalance between RANKL and OPG in bone tissue?

    <p>Unbalanced bone remodeling</p> Signup and view all the answers

    What is the function of osteoblasts in bone remodeling?

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

    What is the primary function of the RANK-RANKL-OPG system in bone remodeling?

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

    Study Notes

    Bone Structure and Composition

    • Bone is a dynamic, mineralized connective tissue that undergoes continuous remodeling cycles of resorption and deposition of new bone tissue.
    • Type I collagen is the major protein in bone, with type V collagen and non-collagenous proteins also present.
    • Bone-specific proteins include chondroitin sulfate proteoglycan, osteocalcin, and bone sialoprotein.
    • Crystalline hydroxyapatite (Ca10(PO4)6(OH)2) confers strength and resilience to bone, along with other inorganic compounds like Na+, Mg2+, CO3²-, and F-.

    Non-Collagenous Proteins of Bone

    • These proteins account for 10-15% of bone protein mass, but are as common as collagen on a molar basis.
    • Most non-collagenous proteins are synthesized by osteoblasts, but some arrive in bone via the circulation.
    • Examples include versican, decorin, biglycan, and osteonectin, which may influence cellular proliferation and differentiation.

    Osteoblasts and Osteoclasts

    • Osteoblasts are specialized cells responsible for synthesizing and secreting organic compounds of bone, such as collagen and proteins.
    • Osteoclasts are multinucleated giant cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.

    Bone Remodeling and Calcium Homeostasis

    • Bone remodeling involves resorption and deposition of new bone tissue, with 4% of compact bone and 20% of trabecular bone renewed annually in healthy adults.
    • Calcitropic hormones, such as PTH, calcitriol, and calcitonin, regulate calcium homeostasis and bone remodeling.

    Alkaline Phosphatase and Osteonectin

    • Alkaline phosphatase (ALP) is an enzyme that hydrolyzes phosphate esters to generate inorganic phosphate ions needed for hydroxyapatite crystals.
    • Osteonectin is a phosphorylated glycoprotein that regulates both cellular activity and matrix mineralization.

    Osteocytes and Bone Remodeling

    • Osteocytes play a key role in regulating bone remodeling, particularly at sites of skeletal microdamage.
    • Osteocytes produce sclerostin, an inhibitor of osteoblast differentiation and function, and fibroblast growth factor 23 (FGF23), which regulates phosphate metabolism.

    Osteoclasts and Bone Resorption

    • Osteoclasts are multinucleated cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.
    • Osteoclasts are inhibited by calcitonin and activated by PTH, 1,25(OH)2D, PGE2, and IL-11.

    Cartilage Structure and Function

    • Cartilage is a specialized connective tissue composed of chondrocytes, collagen, and proteoglycans.
    • The major proteoglycan in cartilage is aggrecan, which contributes to development, tensile strength, and resilience.

    Cartilage Turnover and Disease

    • Cartilage exhibits slow but continuous turnover, regulated by anabolic and catabolic factors such as TGF-β, IGF-I, and proteases.
    • Inflammatory responses and autoimmune attacks can disrupt cartilage homeostasis, leading to diseases such as achondroplasia.

    Bone Structure and Composition

    • Bone is a dynamic, mineralized connective tissue that undergoes continuous remodeling cycles of resorption and deposition of new bone tissue.
    • Type I collagen is the major protein in bone, with type V collagen and non-collagenous proteins also present.
    • Bone-specific proteins include chondroitin sulfate proteoglycan, osteocalcin, and bone sialoprotein.
    • Crystalline hydroxyapatite (Ca10(PO4)6(OH)2) confers strength and resilience to bone, along with other inorganic compounds like Na+, Mg2+, CO3²-, and F-.

    Non-Collagenous Proteins of Bone

    • These proteins account for 10-15% of bone protein mass, but are as common as collagen on a molar basis.
    • Most non-collagenous proteins are synthesized by osteoblasts, but some arrive in bone via the circulation.
    • Examples include versican, decorin, biglycan, and osteonectin, which may influence cellular proliferation and differentiation.

    Osteoblasts and Osteoclasts

    • Osteoblasts are specialized cells responsible for synthesizing and secreting organic compounds of bone, such as collagen and proteins.
    • Osteoclasts are multinucleated giant cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.

    Bone Remodeling and Calcium Homeostasis

    • Bone remodeling involves resorption and deposition of new bone tissue, with 4% of compact bone and 20% of trabecular bone renewed annually in healthy adults.
    • Calcitropic hormones, such as PTH, calcitriol, and calcitonin, regulate calcium homeostasis and bone remodeling.

    Alkaline Phosphatase and Osteonectin

    • Alkaline phosphatase (ALP) is an enzyme that hydrolyzes phosphate esters to generate inorganic phosphate ions needed for hydroxyapatite crystals.
    • Osteonectin is a phosphorylated glycoprotein that regulates both cellular activity and matrix mineralization.

    Osteocytes and Bone Remodeling

    • Osteocytes play a key role in regulating bone remodeling, particularly at sites of skeletal microdamage.
    • Osteocytes produce sclerostin, an inhibitor of osteoblast differentiation and function, and fibroblast growth factor 23 (FGF23), which regulates phosphate metabolism.

    Osteoclasts and Bone Resorption

    • Osteoclasts are multinucleated cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.
    • Osteoclasts are inhibited by calcitonin and activated by PTH, 1,25(OH)2D, PGE2, and IL-11.

    Cartilage Structure and Function

    • Cartilage is a specialized connective tissue composed of chondrocytes, collagen, and proteoglycans.
    • The major proteoglycan in cartilage is aggrecan, which contributes to development, tensile strength, and resilience.

    Cartilage Turnover and Disease

    • Cartilage exhibits slow but continuous turnover, regulated by anabolic and catabolic factors such as TGF-β, IGF-I, and proteases.
    • Inflammatory responses and autoimmune attacks can disrupt cartilage homeostasis, leading to diseases such as achondroplasia.

    Bone Structure and Composition

    • Bone is a dynamic, mineralized connective tissue that undergoes continuous remodeling cycles of resorption and deposition of new bone tissue.
    • Type I collagen is the major protein in bone, with type V collagen and non-collagenous proteins also present.
    • Bone-specific proteins include chondroitin sulfate proteoglycan, osteocalcin, and bone sialoprotein.
    • Crystalline hydroxyapatite (Ca10(PO4)6(OH)2) confers strength and resilience to bone, along with other inorganic compounds like Na+, Mg2+, CO3²-, and F-.

    Non-Collagenous Proteins of Bone

    • These proteins account for 10-15% of bone protein mass, but are as common as collagen on a molar basis.
    • Most non-collagenous proteins are synthesized by osteoblasts, but some arrive in bone via the circulation.
    • Examples include versican, decorin, biglycan, and osteonectin, which may influence cellular proliferation and differentiation.

    Osteoblasts and Osteoclasts

    • Osteoblasts are specialized cells responsible for synthesizing and secreting organic compounds of bone, such as collagen and proteins.
    • Osteoclasts are multinucleated giant cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.

    Bone Remodeling and Calcium Homeostasis

    • Bone remodeling involves resorption and deposition of new bone tissue, with 4% of compact bone and 20% of trabecular bone renewed annually in healthy adults.
    • Calcitropic hormones, such as PTH, calcitriol, and calcitonin, regulate calcium homeostasis and bone remodeling.

    Alkaline Phosphatase and Osteonectin

    • Alkaline phosphatase (ALP) is an enzyme that hydrolyzes phosphate esters to generate inorganic phosphate ions needed for hydroxyapatite crystals.
    • Osteonectin is a phosphorylated glycoprotein that regulates both cellular activity and matrix mineralization.

    Osteocytes and Bone Remodeling

    • Osteocytes play a key role in regulating bone remodeling, particularly at sites of skeletal microdamage.
    • Osteocytes produce sclerostin, an inhibitor of osteoblast differentiation and function, and fibroblast growth factor 23 (FGF23), which regulates phosphate metabolism.

    Osteoclasts and Bone Resorption

    • Osteoclasts are multinucleated cells that resorb bone tissue, regulated by the RANK-RANKL-OPG system.
    • Osteoclasts are inhibited by calcitonin and activated by PTH, 1,25(OH)2D, PGE2, and IL-11.

    Cartilage Structure and Function

    • Cartilage is a specialized connective tissue composed of chondrocytes, collagen, and proteoglycans.
    • The major proteoglycan in cartilage is aggrecan, which contributes to development, tensile strength, and resilience.

    Cartilage Turnover and Disease

    • Cartilage exhibits slow but continuous turnover, regulated by anabolic and catabolic factors such as TGF-β, IGF-I, and proteases.
    • Inflammatory responses and autoimmune attacks can disrupt cartilage homeostasis, leading to diseases such as achondroplasia.

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    Description

    This quiz covers the structure and composition of bones, including the proteins and minerals that make up bone tissue. It also explores the process of bone remodeling and the properties that give bone its strength and resilience.

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