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Questions and Answers
What is one of the primary functions of bones in the human body?
What is one of the primary functions of bones in the human body?
Which of the following is NOT a category of bone shape?
Which of the following is NOT a category of bone shape?
What type of bone develops in tendons under stress?
What type of bone develops in tendons under stress?
Which structure is known as the shaft of a long bone?
Which structure is known as the shaft of a long bone?
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What is the primary function of osteocytes in bone tissue?
What is the primary function of osteocytes in bone tissue?
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Which of the following best describes the matrix composition of bone tissue?
Which of the following best describes the matrix composition of bone tissue?
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Which cells are responsible for breaking down bone tissue?
Which cells are responsible for breaking down bone tissue?
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What is the function of articular cartilage in long bones?
What is the function of articular cartilage in long bones?
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What provides the hardness of bone?
What provides the hardness of bone?
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Which of the following structures house osteocytes in compact bone?
Which of the following structures house osteocytes in compact bone?
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What is the main distinction between compact bone and spongy bone?
What is the main distinction between compact bone and spongy bone?
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Osteogenesis refers to which process in the human body?
Osteogenesis refers to which process in the human body?
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Which type of ossification primarily forms flat bones such as those of the skull?
Which type of ossification primarily forms flat bones such as those of the skull?
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What is found in the spaces of spongy bone that supports blood cell production?
What is found in the spaces of spongy bone that supports blood cell production?
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Which feature describes the arrangement of osteons in compact bone?
Which feature describes the arrangement of osteons in compact bone?
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What term describes the removal of older osteons during bone remodeling?
What term describes the removal of older osteons during bone remodeling?
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What is the primary function of the zone of resting cartilage in the epiphyseal plate?
What is the primary function of the zone of resting cartilage in the epiphyseal plate?
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At what age do the epiphyseal plates typically close, marking the end of growth in length for bones?
At what age do the epiphyseal plates typically close, marking the end of growth in length for bones?
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Which zone of the epiphyseal plate is characterized by rapid cell division and appears as stacked coins?
Which zone of the epiphyseal plate is characterized by rapid cell division and appears as stacked coins?
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What process is responsible for the increase in thickness or diameter of bones?
What process is responsible for the increase in thickness or diameter of bones?
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What happens to cartilage cells in the zone of calcified cartilage?
What happens to cartilage cells in the zone of calcified cartilage?
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What is the role of osteoclasts in the epiphyseal plate?
What is the role of osteoclasts in the epiphyseal plate?
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What occurs after the periosteal cells differentiate into osteoblasts during bone growth in thickness?
What occurs after the periosteal cells differentiate into osteoblasts during bone growth in thickness?
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Which of the following statements about bone fractures is true?
Which of the following statements about bone fractures is true?
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What is the logical sequence of events in the intramembranous ossification process?
What is the logical sequence of events in the intramembranous ossification process?
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Which of the following bones is primarily formed by endochondral ossification?
Which of the following bones is primarily formed by endochondral ossification?
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What initiates the calcification during endochondral ossification?
What initiates the calcification during endochondral ossification?
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What role do osteoclasts play in the development of a medullary cavity during ossification?
What role do osteoclasts play in the development of a medullary cavity during ossification?
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How does the growth in length of a bone primarily occur?
How does the growth in length of a bone primarily occur?
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Which structure remains as cartilage at the ends of long bones after endochondral ossification?
Which structure remains as cartilage at the ends of long bones after endochondral ossification?
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What is the primary function of the periosteal bud in the ossification process?
What is the primary function of the periosteal bud in the ossification process?
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What type of growth allows a cartilage model to increase in width during endochondral ossification?
What type of growth allows a cartilage model to increase in width during endochondral ossification?
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Study Notes
Functions of Bone
- Protects and supports soft tissues
- Provides attachment sites for muscles, enabling movement
- Stores minerals calcium and phosphate, crucial for mineral homeostasis
- Produces blood cells in red bone marrow (hemopoiesis)
- Stores energy in yellow bone marrow
Classification of Bone Shape
- Long Bones: Longer than wide, cylindrical shape (e.g., femur, phalanges)
- Short Bones: Nearly equal in width and length, cube-shaped (e.g., carpals, tarsals)
- Flat Bones: Thin and flat (e.g., skull bones, sternum, ribs, shoulder blades)
- Irregular Bones: Complex shape, don't fit other categories (e.g., vertebrae, hip bones)
- Sesamoid Bones: Develop within tendons under friction and stress (e.g., patella)
- Sutural Bones: Classified by location, tiny bones in sutures between cranial bones
Anatomy of a Long Bone
- Diaphysis: Shaft of the bone
- Epiphysis: Ends of the long bone
- Metaphyses: Areas between epiphysis and diaphysis, containing the epiphyseal plate in growing bones
- Articular Cartilage: Covers joint surfaces, reduces friction and acts as a shock absorber
- Medullary Cavity: Marrow cavity within the diaphysis
- Endosteum: Lining of the marrow cavity
- Periosteum: Tough membrane covering bone (excluding cartilage)
Histology of Bone Tissue
- Connective tissue with widely spaced cells
- Matrix composed of 25% water, 25% collagen fibers, and 50% mineral salts
- Minerals: Primarily hydroxyapatite (85%), calcium carbonate (10%), and others like calcium fluoride, magnesium fluoride
- Four types of bone cells:
- Osteogenic Cells: Divide and differentiate into osteoblasts
- Osteoblasts: Bone-building cells
- Osteocytes: Mature bone cells, maintain bone tissue
- Osteoclasts: Derived from monocytes, break down bone tissue
Matrix of Bone
- Inorganic Mineral Salts: Provide bone's hardness (hydroxyapatite and calcium carbonate)
- Organic Collagen Fibers: Provide bone's flexibility, resist stretching and tearing
- Bone is not solid, contains spaces for vessels and red bone marrow
- Spongy Bone: Many spaces
- Compact Bone: Fewer spaces
Compact Bone
- Arranged in units called osteons
- Osteons contain:
- Blood vessels, lymphatic vessels
- Nerves, osteocytes
- Calcified matrix
- Aligned along lines of stress, which can change over time
- Concentric rings (lamellae): Calcified matrix surrounding a central blood vessel
- Lacunae: Spaces containing osteocytes
- Canaliculi: Tiny canals filled with extracellular fluid, connecting osteocytes
Spongy Bone
- Lacks osteons
- Consists of trabeculae surrounding red marrow-filled spaces
- Forms most of the structure in short, flat, and irregular bones, and epiphyses of long bones
- Lightweight, supports and protects red bone marrow
Trabeculae of Spongy Bone
- Latticework of thin bone plates aligned along lines of stress
- Spaces between trabeculae filled with red marrow
Bone Formation (Osteogenesis or Ossification)
- Begins with mesenchymal cells forming template for ossification
- Two types:
- Intramembranous Ossification: Bone formation directly from fibrous connective tissue membranes
- Endochondral Ossification: Bone formation from hyaline cartilage models
Intramembranous Ossification
- Forms flat bones of skull, mandible, and clavicles
- Ossification Center: Mesenchymal cells convert to osteoblasts and lay down osteoid matrix
- Matrix calcifies as osteoblasts become osteocytes, forming bridges of trabeculae
- Peripheral mesenchyme forms periosteum
Endochondral Ossification
- Replaces cartilage with bone, forms most bones
- Development of Cartilage Model: Mesenchymal cells form cartilage model
-
Growth of Cartilage Model:
- Interstitial Growth: Chondrocyte cell division and matrix formation, lengthens cartilage
- Appositional Growth: New matrix formation on periphery by chondroblasts, widens cartilage
- Calcification: Cells in midregion burst, trigger calcification and chondrocyte death
Endochondral Ossification (Continued)
-
Development of Primary Ossification Center:
- Periosteal Bone Collar: Perichondrium lays down bone collar
- Nutrient Artery: Penetrates cartilage model center
- Periosteal Bud: Brings osteoblasts and osteoclasts, forming spongy bone trabeculae
- Medullary Cavity: Formed by osteoclasts
Endochondral Ossification (Continued)
- Development of Secondary Ossification Center: Blood vessels enter epiphyses near birth, forming spongy bone without a medullary cavity
- Formation of Articular Cartilage: Cartilage on bone ends remains as articular cartilage
Growth in Length
- Epiphyseal plate (growth plate) is crucial for bone growth in length
-
Zones of Epiphyseal Plate:
- Zone of Resting Cartilage: Anchors plate to bone
- Zone of Proliferating Cartilage: Rapid cell division
- Zone of Hypertrophic Cartilage: Enlarged cells remain in columns
- Zone of Calcified Cartilage: Thin zone, cells dead, matrix calcified, osteoclasts remove matrix, osteoblasts and capillaries form bone
Growth in Thickness (Appositional Growth)
- Bone grows in thickness by appositional growth at bone surface
-
Process:
- Periosteal cells differentiate into osteoblasts, forming matrix
- Ridges fuse, periosteum becomes endosteum
- New concentric lamellae form
- Osteoblasts under periosteum form circumferential lamellae
Fractures
- Broken bones
- Typically heal on their own, but repositioning is necessary for proper healing.
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Description
This quiz covers the essential functions of bone, classifications of bone shapes, and the specific anatomy of long bones. Understand the protective, supportive, and mineral-storage roles of bones, along with details about different bone types and structures.
