Copyright © 2019, Elsevier Inc. All Rights Reserved. 1Chapter 44: Structure and Function of the Musculoskeletal SystemMcCance/Huether: Pathophysiology: The Biologic Basis of Disease in Adults and Children, 8th EditionMULTIPLE CHOICE 1. Which bone cells produce osteocalcin when stimulated by 1,25-dihydroxyvitamin D and synthesize osteoid?a. Osteoclastsb. Osteocytesc. Fibrocytesd. OsteoblastsANS: DOsteoblasts are cells derived from mesenchymal stem cells and produce several substances, including osteocalcin, transforming growth factor-beta (TGF-β) (a growth inhibitor for many cells), macrophage colony-stimulating factor, receptor activator of nuclear factor kappa-B ligand, osteoprotegerin (OPG), and bone matrix when stimulated by 1,25-dihydroxyvitamin D. Osteoclasts are bone resorbing cells. Osteocytes are the most abundant cells in bone. Fibrocytes produce connective tissue proteins.PTS: 1 DIF: Cognitive Level: Remembering 2. What happens to the original bone during the second phase of bone remodeling?a. The original bone is replaced.b. It hardens.c. The original bone is resorbed.d. It is synthesized.ANS: CIn the second phase of remodeling (resorption), the osteoclasts form a cutting cone that gradually resorbs bone, leaving behind an elongated cavity termed a resorption cavity. The original bone is replaced during phase 3. The bone hardens in a process called calcification where minerals are deposited and crystalize. Osteoblasts initiate the formation of new bone by their synthesis of osteoid (nonmineralized bone matrix).PTS: 1 DIF: Cognitive Level: Remembering 3. Which cells function to maintain bone matrix?a. Osteoclastsb. Osteocytesc. Osteoblastsd. OsteophytesANS: BOsteocytes help synthesize and replace needed elements of the matrix by signaling osteoclasts and osteoblasts to resorb and form new bone. Osteoclasts are bone resorbing cells. Osteoblasts are bone forming cells. Osteophytes are bony outgrowths, also known as bone spurs.PTS: 1 DIF: Cognitive Level: Remembering 4. Which bone cells are large and multinucleated and contain lysosomes filled with hydrolytic enzymes?a. Osteoblastsb. Osteoclastsc. Osteocytesd. FibrocytesANS: BOsteoclasts are the major resorptive cells of bone. They are large multinucleated cells with a short life span and contain lysosomes (digestive vacuoles) filled with hydrolytic enzymes. Osteoblasts are bone forming cells. Osteoclasts are bone resorbing cells. Fibrocytes produce connective tissue proteins.PTS: 1 DIF: Cognitive Level: Remembering 5. Which bone cell secretes hydrochloric acid to help dissolve bone minerals and collagenase, thus aiding in the digestion of collagen?a. Osteocytesb. Osteoblastsc. Osteoclastsd. OsteophytesANS: COsteoclasts bind to the bone surface of cell attachment proteins called integrins. They bring about resorption of bone by secreting hydrochloric acid and cathepsin K (a protease enzyme) that help dissolve bone minerals and collagenase, which aids in digesting collagen, along with the action of cytokines. Osteocytes are the most abundant cells in bone. Osteoblasts are bone forming cells. Osteophytes are bony outgrowths, otherwise known as bone spurs.PTS: 1 DIF: Cognitive Level: RememberingCopyright © 2019, Elsevier Inc. All Rights Reserved. 2 6. Which glucoprotein is believed to inhibit calcium phosphate precipitation and play a part in bone resorption by recruiting osteoclasts?a. Osteocalcinb. Osteonectinc. Laminind. OsteopontinANS: AThe roles of osteocalcin may be to inhibit calcium phosphate precipitation and play a part in bone resorption by recruiting osteoclasts. Osteonectin is a bone-specific protein that binds selectively to both hydroxyapatite and collagen in the bone matrix. Laminin is an abundant bone matrix protein in humans that stabilizes basement membranes in bones and is important in neurite and axon growth. Osteopontin is a noncollagenous bone matrix protein.PTS: 1 DIF: Cognitive Level: Remembering 7. Which glucoprotein is thought to transport essential elements such as hormones, ions, and other metabolites to and from the bone cells?a. Osteocalcinb. Osteonectinc. Laminind. Bone albuminANS: DResearchers believe bone albumin transports essential elements such as hormones, ions, and other metabolites to and from the bone cells and maintain the osmotic pressure of bone fluid (fluid surrounding mineral crystals and osteoblasts). Osteocalcin inhibits calcium phosphate precipitation and recruits osteoclasts for bone resorption. Osteonectin is a bone-specific protein that binds selectively to both hydroxyapatite and collagen in the bone matrix. Laminin is an abundant bone matrix protein in humans that stabilizes basement membranes in bones and is important in neurite and axon growth.PTS: 1 DIF: Cognitive Level: Remembering 8. How is the work function of a muscle usually calculated?a. Muscle typeb. Calculating force × distancec. Foot poundsd. KilogramsANS: BThe ultimate function of muscle is to accomplish work. Work refers to the amount of energy liberated or the amount of force exerted over a distance (work = force × distance). Muscle type is not relevant. Work is sometimes expressed in measures such as foot-pounds or kilogram-meters.PTS: 1 DIF: Cognitive Level: Remembering 9. What is the basic structural unit in compact bone?a. Small channels called canaliculib. Osteocytes within the lacunaec. Tiny spaces within the lacunaed. Haversian systemANS: DThe basic structural unit in compact bone is the haversian system. Osteocytes are interconnected by a network of dendritic cytoplasmic processes through tunnels known as canaliculi. These canaliculi radiate from each lacuna and contain cell processes from the resident osteocyte, thereby enabling it to form gap junctions with adjacent osteocytes. Lacunae each contain one osteocyte.PTS: 1 DIF: Cognitive Level: Remembering 10. Which part of an injured joint becomes insensitive to pain and regenerates slowly and minimally?a. Synoviumb. Articular cartilagec. Bursad. TendonANS: BArticular cartilage has no blood vessels, lymph vessels, or nerves. Therefore, it is insensitive to pain and regenerates slowly and minimally after injury. This is not true of the synovium, bursa, or tendons.PTS: 1 DIF: Cognitive Level: RememberingCopyright © 2019, Elsevier Inc. All Rights Reserved. 3 11. The outer layer of the periosteum contains blood vessels and nerves that penetrate the inner structures of the bone by way of which structure?a. Volkmann
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