T3 L1: Physiology of Bone Repair (HJW)
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Questions and Answers

Which of the following is responsible for bone degradation and remodeling?

  • Osteoblasts
  • Osteocytes
  • Osteoclasts (correct)
  • Osteopetrosis

    • What is the composition of bone primarily made up of?

  • Cells and proteins
  • Inorganic substances
  • Minerals
  • Extracellular matrix (correct)

    • Which bone classification is characterized by spicules and trabeculae?

  • Woven bone
  • Cancellous bone (correct)
  • Lamellar bone
  • Cortical bone

    • What is the function of osteoblasts?

    <p>Protein production and bone growth</p> Signup and view all the answers

    What is the clinical term for an imbalance between bone resorption and bone formation?

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

    Which cells are responsible for bone resorption?

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

    Which cells are responsible for resorbing bone?

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

    What is the main component of the extracellular matrix in bone?

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

    What is the function of osteoclasts in bone remodeling?

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

    What is the role of glycosaminoglycans in the extracellular matrix of bone?

    <p>Attract water</p> Signup and view all the answers

    What are the two major factors governing bone remodeling?

    <p>Mechanical stress and calcium homeostasis</p> Signup and view all the answers

    What happens to bone when it is not subjected to weight-bearing or mechanical stress?

    <p>It weakens</p> Signup and view all the answers

    Which hormone is responsible for increasing plasma calcium levels?

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

    What is the active form of vitamin D?

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

    What is the main factor determining peak bone mass?

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

    What is the effect of intermittent PTH compared to continuous PTH?

    <p>Continuous PTH has stronger effects</p> Signup and view all the answers

    What are the signs and symptoms of hypercalcemia?

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

    What can cause chronic hypocalcemia?

    <p>Parathyroid dysfunction</p> Signup and view all the answers

    Which substance inhibits osteoclast-mediated bone resorption related to inorganic pyrophosphate?

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

    What is the molecular mechanism of osteopetrosis?

    <p>Defective Vacuolar proton pump</p> Signup and view all the answers

    Which drug is a monoclonal antibody that targets RANKL to prevent osteoclast maturation?

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

    What is the purpose of Teriparatide in the treatment of osteoporosis?

    <p>Encourage osteoblast formation of bone</p> Signup and view all the answers

    What is the function of Carbonic Anhydrase in osteoclasts?

    <p>Secrete acid for bone resorption</p> Signup and view all the answers

    During which phase of fracture healing does lamellar bone replace woven bone?

    <p>Hard Callus Formation</p> Signup and view all the answers

    Which of the following is NOT a learning outcome of the Structures & Cells of bone section?

    <p>Pathologies of Calcium Regulation</p> Signup and view all the answers

    What is the main focus of the chapter 'Bone Tissue' in the book 'Tortora' (14th ed.)?

    <p>Pathologies of Bone Remodeling</p> Signup and view all the answers

    Which hormone plays a role in calcium regulation?

    <p>All of the above</p> Signup and view all the answers

    What is the email address of Professor Harry Witchel?

    <p><a href="mailto:[email protected]">[email protected]</a></p> Signup and view all the answers

    What is the main focus of the chapter 'Calcium' in the book 'Guyton & Hall' (13th ed.)?

    <p>Calcium homeostasis</p> Signup and view all the answers

    What is a common cause of osteoporosis?

    <p>Introduction to Drugs for Osteoporosis</p> Signup and view all the answers

    Which cells are responsible for maintaining the bone?

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

    What is the main inorganic component of bone?

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

    What is the function of osteoclasts in bone degradation?

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

    Where do osteocytes live within the bone?

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

    Which cells are responsible for bone resorption?

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

    Which component of bone provides its tensile strength?

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

    What is the primary function of osteoblasts?

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

    What is the main role of osteoclasts in bone remodeling?

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

    What is the main focus of the chapter 'Calcium' in the book 'Guyton & Hall' (13th ed.)?

    <p>The physiology of calcium regulation</p> Signup and view all the answers

    What is the main factor determining peak bone mass?

    <p>Genetics and heredity</p> Signup and view all the answers

    What is a common cause of osteoporosis?

    <p>Smoking and alcohol consumption</p> Signup and view all the answers

    What is the function of osteoclasts in bone remodeling?

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

    Which cells detect mechanical stress in bone?

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

    What happens to bone when it is not subjected to weight-bearing or mechanical stress?

    <p>It undergoes rapid turnover</p> Signup and view all the answers

    What are the two major factors governing bone remodeling?

    <p>Gravity and calcium homeostasis</p> Signup and view all the answers

    What is the function of bisphosphonates in the treatment of osteoporosis?

    <p>They inhibit osteoclast-mediated resorption</p> Signup and view all the answers

    Which substance in the extracellular matrix of bone attracts water and provides squishiness and resistance to compression?

    <p>Glycosylated glycans</p> Signup and view all the answers

    Which cells are responsible for releasing growth factors in the extracellular matrix of bone?

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

    What is the process called when bone cells recognize bone stresses and stimulate the remodeling process?

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

    What is the main function of hydroxyapatite in the extracellular matrix of bone?

    <p>Acts as a reinforcement like steel in reinforced concrete</p> Signup and view all the answers

    What is the main focus of the chapter 'Bone Tissue' in the book 'Tortora' (14th ed.)?

    <p>The composition of bone tissue</p> Signup and view all the answers

    What is the main function of osteoblasts?

    <p>To produce protein in the extracellular matrix</p> Signup and view all the answers

    What is the difference between lamellar bone and woven bone?

    <p>Lamellar bone is more mature and organized than woven bone</p> Signup and view all the answers

    What are the three types of bone cells and their functions?

    <p>Osteoblasts - bone formation, Osteocytes - bone growth, Osteoclasts - bone resorption</p> Signup and view all the answers

    Which of the following is a function of inorganic phosphate in bone metabolism?

    <p>It accumulates on bone and interferes with osteoblast metabolism</p> Signup and view all the answers

    What is the effect of bisphosphonates like alendronate on osteoclasts?

    <p>They inhibit osteoclast-mediated bone resorption</p> Signup and view all the answers

    What happens to osteoclasts when inorganic phosphate interferes with bone turnover?

    <p>They become less active</p> Signup and view all the answers

    What is the main role of osteoblasts in bone metabolism?

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

    What is the effect of bisphosphonates on osteoblasts?

    <p>They inhibit osteoblast-mediated bone resorption</p> Signup and view all the answers

    What is the role of inorganic phosphate in bone turnover?

    <p>To interfere with osteoblast metabolism</p> Signup and view all the answers

    Which of the following is NOT a symptom/sign of acute hypocalcaemia?

    <p>Low mood</p> Signup and view all the answers

    Which of the following is a symptom/sign of chronic hypocalcaemia?

    <p>Carpopedal spasm</p> Signup and view all the answers

    Which of the following is a symptom/sign of acute hypercalcaemia?

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

    Name one function of the skeleton.

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

    Name one organ that is affected by PTH.

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

    What is the cause of autosomal dominant osteopetrosis?

    <p>Vitamin D deficiency</p> Signup and view all the answers

    What is the primary molecule responsible for bone's compressive strength?

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

    What is the main function of osteocytes in bone?

    <p>Bone maintenance and stress detection</p> Signup and view all the answers

    What is the main difference between intramembranous and endochondral bone formation?

    <p>Intramembranous begins with ossification while endochondral begins with cartilage</p> Signup and view all the answers

    What is the main function of osteoblasts in bone metabolism?

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

    What is the name of the depression formed around an osteoclast when it is degrading bone?

    <p>Howship's lacuna</p> Signup and view all the answers

    What is the main role of glycosaminoglycans in bone?

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

    What is the main function of osteoclasts in bone remodeling?

    <p>To secrete acid and digest hydroxyapatite</p> Signup and view all the answers

    What is the main function of osteoblasts in bone metabolism?

    <p>To lay down bone and increase bone density</p> Signup and view all the answers

    What is the main factor determining peak bone mass?

    <p>Genetic material</p> Signup and view all the answers

    What is the primary function of osteocytes?

    <p>To maintain osteoid and provide mechanical support</p> Signup and view all the answers

    What is the main focus of the chapter 'Calcium' in the book 'Guyton & Hall' (13th ed.)?

    <p>Calcium regulation</p> Signup and view all the answers

    What are the signs and symptoms of hypercalcemia?

    <p>Bleeding and cardiac arrhythmias</p> Signup and view all the answers

    Which of the following is the main reason why bisphosphonates accumulate to a high concentration only in bones?

    <p>Bisphosphonates have a high affinity for calcium ions</p> Signup and view all the answers

    Why is the oral bioavailability of bisphosphonates low?

    <p>Bisphosphonates have a highly negative charge</p> Signup and view all the answers

    What is the main effect of Teriparatide on bone remodeling?

    <p>Increased osteoblast activity</p> Signup and view all the answers

    What is the net effect of intermittent PTH administration on bone remodeling?

    <p>Increased osteoblast number and activity</p> Signup and view all the answers

    What is the role of osteoblasts in bone metabolism?

    <p>Laying down bone and activating osteoclast precursors</p> Signup and view all the answers

    What is the main effect of bisphosphonate-based drugs on calcium ions?

    <p>They bind to calcium ions</p> Signup and view all the answers

    Which of the following pharmacological treatments for osteoporosis mimics pyrophosphate in bone and leads to osteoclast apoptosis or protein trafficking defects?

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

    Which of the following drugs is a monoclonal antibody that binds to the RANK ligand and prevents activation and differentiation of osteoclasts?

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

    Why is the high percentage of inorganic material in bone unusual in a living system?

    <p>Inorganic material cannot be manipulated directly by enzymatic activity.</p> Signup and view all the answers

    How do calcium phosphate crystals form where bone is needed?

    <p>Calcium and phosphate are at a high concentration and can crystalize out of solution.</p> Signup and view all the answers

    Why doesn't calcium phosphate fall out of solution in plasma?

    <p>There are crystallization inhibitors in the plasma.</p> Signup and view all the answers

    Why does hypocalcemia lead to convulsions and why are its effects on the ECG 'paradoxical'?

    <p>Hypocalcemia makes membranes 'more excitable' and 'less stable', leading to convulsions. The effects on the ECG are 'paradoxical' because hypocalcemia decreases the QT interval.</p> Signup and view all the answers

    Study Notes

    Bone Structure and Function

    • Osteoclasts are responsible for bone degradation and remodeling.
    • Bone is primarily composed of organic matrix (collagen) and inorganic components (hydroxyapatite).
    • Spongy bone classification is characterized by spicules and trabeculae.
    • Osteoblasts function in bone formation by synthesizing the bone matrix.
    • An imbalance between bone resorption and formation is referred to as osteoporosis.

    Bone Cells and Their Roles

    • Osteoclasts resorb bone by breaking down the mineral matrix and collagen.
    • Osteoblasts are essential for building bone and secreting bone matrix proteins.
    • Osteocytes, derived from osteoblasts, maintain bone tissue and detect mechanical stress.
    • Glycosaminoglycans in the extracellular matrix attract water, providing compressive resistance.

    Bone Remodeling and Influencing Factors

    • Two major factors governing bone remodeling are mechanical stress and hormonal signals.
    • Lack of weight-bearing or mechanical stress leads to bone loss or atrophy.
    • Parathyroid hormone (PTH) increases plasma calcium levels.
    • The active form of vitamin D is calcitriol.

    Hormonal and Mechanical Influences

    • Peak bone mass is influenced primarily by genetic factors and physical activity.
    • Intermittent PTH promotes bone formation, while continuous PTH can lead to bone resorption.
    • Hypercalcemia symptoms include confusion, muscle weakness, and kidney stones.
    • Chronic hypocalcemia can be caused by vitamin D deficiency or hypoparathyroidism.

    Pharmacological Treatments and Mechanisms

    • Inorganic pyrophosphate inhibits osteoclast-mediated bone resorption.
    • Osteopetrosis arises from impaired osteoclast function due to genetic mutations.
    • RANKL-targeting monoclonal antibodies, such as denosumab, prevent osteoclast maturation.
    • Teriparatide, a recombinant form of PTH, promotes bone formation in osteoporosis.

    Fracture Healing and Bone Types

    • During fracture healing, lamellar bone replaces woven bone in the remodeling phase.
    • Lamellar bone exhibits a parallel arrangement of collagen fibers, while woven bone has a haphazard organization.

    Bone Components and Extracellular Matrix

    • Hydroxyapatite provides compressive strength to bone.
    • Proteins in the extracellular matrix attract water and help with the compressive strength of bone.
    • Growth factors released from bone cells aid in the regulation of remodeling.

    Symptoms and Clinical Insights

    • Acute hypocalcemia symptoms include muscle cramps and seizures, while chronic leads to dental issues and brittle nails.
    • Differences between intramembranous (direct ossification) and endochondral (replacement of cartilage) bone formation exist in developmental pathways.

    Additional Insights

    • Osteoclasts create depressions called Howship's lacunae as they degrade bone.
    • The high inorganic content of bone is unusual due to its structure providing rigidity and strength without compromising biological function.
    • Calcium phosphate crystals necessary for bone formation are stable in blood due to regulatory proteins preventing precipitation. Hypocalcemia's neurological effects are linked to altered neuromuscular excitability and can lead to ECG anomalies.

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