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Questions and Answers
What does the outermost layer of a network represent?
What does the outermost layer of a network represent?
- The least secure layer (correct)
- The most secure layer
- The inner core
- The boundary of the network
The innermost layer of a network is represented by the number '0'.
The innermost layer of a network is represented by the number '0'.
True (A)
Identify the most secure layer of the network.
Identify the most secure layer of the network.
inner most layer
The ______ layer is considered the outermost part of the network.
The ______ layer is considered the outermost part of the network.
Match the network layers to their characteristics:
Match the network layers to their characteristics:
Flashcards
Network Layers
Network Layers
Different levels of organization within a network, from the outermost to innermost layers.
Outermost Layer
Outermost Layer
The highest or most external layer of a network.
Innermost Layer
Innermost Layer
The lowest or most internal layer of a network.
Network Structure
Network Structure
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Network
Network
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Study Notes
Bone Histology
- Bone is a highly vascularized connective tissue, its matrix is calcified making it hard and strong; this hardness aids in carrying body weight.
- Bone is composed of three main components: bone cells, fibers, and hard matrix.
- Bone is anatomically classified as: long (e.g., humerus, femur), short (e.g., carpal, tarsal bones), flat (e.g., skull, ribs), and irregular (e.g., vertebrae).
- Bone functions include support, protection, movement, mineral storage, and blood cell formation.
Learning Objectives
- Classify bone anatomically and histologically.
- Identify locations of compact and spongy bones in the human body.
- Understand the microscopic structure of bone.
Histological Classification
Compact Bone
- Composed of solid, dense lamellae (layers) without cavities.
- Found in the shaft (diaphysis) surrounding the medullary canal, covering surfaces of flat, short, and irregular bones.
Cancellous (Spongy) Bone
- Composed of irregular, branching, and anastomosing bony trabeculae.
- Trabeculae enclose bone marrow cavities.
- Located in the interior of flat, short, irregular bones, and the epiphyses of long bones.
Bone Cells
- Osteogenic cells (osteoprogenitor cells): Precursor cells that develop into osteoblasts.
- Osteoblasts: Bone-forming cells that synthesize osteoid tissue (organic part of bone matrix). Osteoid is the newly formed bone matrix prior to mineralization.
- Osteocytes: Mature bone cells; housed within lacunae; maintain bone's hardness.
- Osteoclasts: Large, multinucleated cells that resorb or break down bone. Situated in Howship's lacunae (shallow depressions) along bone surfaces. These cells work by releasing hydrogen ions (H+) and secreting lysosomal enzymes.
Structure of Compact Bone
- Periosteum: Outer fibrous connective tissue layer covering the bone.
- External circumferential lamellae: Parallel lamellae beneath the periosteum.
- Haversian system (osteon): Cylindrical structural unit containing concentric lamellae surrounding a central canal (Haversian canal); this canal contains blood vessels, nerves, and loose connective tissue.
- Interstitial lamellae: Irregularly arranged lamellae filling spaces between osteons.
- Internal circumferential lamellae: Parallel lamellae surrounding the endosteum.
- Endosteum: Inner layer lining the marrow cavity, composed of a single layer of osteoblasts.
Structure of Spongy Bone
- Composed of branching, anastomosing trabeculae.
- Trabeculae contain bone marrow cavities within them.
- Trabeculae are created by irregularly arranged lamellae enclosing osteocytes.
- Unlike compact bone, spongy bone does not contain osteons.
Reference Material
- Junqueira's Basic Histology, 13th Edition (2013), by Anthony L. Mescher
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