Hubs-4-Revision3

In an experiment, bone samples are treated to remove either organic or inorganic components. Which results would you expect, and why?

Removing inorganic components makes the bone brittle, as hydroxyapatite resists tension

Removing organic components makes the bone brittle, as proteoglycans resist bending forces

Removing organic components makes the bone flexible, as collagen resists compression

Removing inorganic components makes the bone flexible, as hydroxyapatite resists compression

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Which condition is characterized by a loss of cortical bone and thinning of trabeculae?

Osteogenesis imperfecta

Osteopenia

Osteoporosis

Osteosarcoma

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Which structural feature of compact bone allows it to resist compressive forces while maintaining overall rigidity?

Central canals, which house blood vessels to strengthen the matrix

Collagen fibers in the organic matrix, which align to absorb compressive stress

Trabeculae within osteons, which distribute force throughout the matrix

Hydroxyapatite crystals in the inorganic matrix, which reinforce lamellae

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What is the main structural difference between compact and cancellous bone?

Compact bone lacks osteons, while cancellous bone contains them

Compact bone is lighter, while cancellous bone is heavier

Compact bone is dense, while cancellous bone contains trabeculae

Compact bone contains trabeculae, while cancellous bone is dense

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Which feature of bone ECM contributes most significantly to its ability to resist both compressive and tensile forces, and why?

Proteoglycans, as they support tensile strength and facilitate nutrient transport

Hydroxyapatite and collagen, as they work together to provide both flexibility and compressive strength

Hydroxyapatite, as it provides rigidity and resistance to compression

Collagen, as it aligns parallel to osteons to enhance compressive strength

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Vertebral compression fractures are a common consequence of osteoporosis. Which combination of structural changes in cancellous bone contributes to this, and why is this effect pronounced in the vertebrae?

Thinning and loss of trabeculae disrupts the alignment along stress lines, reducing the vertebrae’s ability to distribute compressive forces

The loss of collagen in cancellous bone leads to brittleness in vertebrae, making them less able to resist multidirectional forces

Increased osteoblast activity thickens cortical bone, but cancellous bone in vertebrae fails to align trabeculae under mechanical load

Osteons in vertebrae are replaced by trabeculae, which lose hydroxyapatite and become unable to resist compressive stress

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A study examines the relationship between osteoclast activity and mechanical load distribution in both compact and cancellous bone. Researchers observe that excessive osteoclast activity in weight-bearing bones leads to localized cortical thinning and widespread trabecular loss. Which combination of structural changes and their functional consequences best explains this observation?

Increased collagen breakdown in compact bone reduces flexibility, while trabecular misalignment in cancellous bone enhances resistance to compressive forces but limits tensile strength

Osteon degradation in compact bone reduces compressive strength, while misaligned trabeculae in cancellous bone weaken resistance to multidirectional forces, increasing fracture risk.

Loss of hydroxyapatite in compact bone reduces resistance to tension, while trabecular thinning in cancellous bone disrupts marrow cavities, limiting nutrient transport

Cortical thinning in compact bone reduces its ability to resist bending forces, while trabecular loss in cancellous bone compromises stress distribution, increasing susceptibility to compression fractures

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How does trabecular alignment benefit cancellous bone?

By optimizing resistance to forces from multiple directions

By forming lamellae around central canals

By reducing bone weight to prevent fractures

By directing forces through a single trabecula

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Bone homeostasis relies on the balance between ______, which deposit bone matrix to maintain structural integrity, and ______, which resorb bone matrix to mobilize minerals. In osteoporosis, this balance shifts toward ______ activity, leading to ______ changes in both compact and cancellous bone

Osteogenic cells; osteoblasts; osteocyte; decreased lamellae formation

Osteocytes; osteoblasts; osteoclast; increased density and brittleness

Osteoclasts; osteocytes; osteoblast; trabecular realignment and cortical expansion

osteoclasts; osteoclast; cortical thinning and trabecular loss

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10.

The ______ are cylindrical units in compact bone, and the ______ inside them provide a pathway for blood vessels and nerves

Osteons; central canals

Lamellae; canaliculi

Lacunae; osteocytes

Trabeculae; lacunae

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