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| <big><center>[[Bones|'''BACK TO BONES''']]</center></big> | | <big><center>[[Bones|'''BACK TO BONES''']]</center></big> |
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− | INTRODUCTION
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− | Bone is a hard, highly specialised connective tissue comprising interconnected cells embedded in a calcified, collagenous matrix. It is a living, dynamic, responsive tissue, growing and remodelling throughout life. The pathogenesis of many bone diseases is complex and may involve genetic defects, diet or infection (or, horror of horrors, a combination of these).
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− | A FEW REMINDERS………
| + | ===Introduction=== |
− | I. NORMAL FUNCTION AND STRUCTURE
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− | Function: Support/protection, movement, stem cell storage, mineral storage | + | *Bone is a hard, highly specialised connective tissue |
− | Structure: Bone is composed of cells and matrix
| + | *Consists of interconnected cells embedded in a calcified, collagenous matrix |
| + | *Living, dynamic, responsive tissue, growing and remodelling throughout life |
| + | *Pathogenesis of many bone diseases is complex |
| + | **May involve genetic defects, diet or infection or a combination of these |
| + | *'''Function''': |
| + | **Support/protection |
| + | **Movement |
| + | **Stem cell storage |
| + | **Mineral storage |
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− | Cells: 1. Osteoblasts
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− | 2. Osteocytes
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− | 3. Osteoclasts
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− | Osteoblasts
| + | ===Normal structure=== |
− | • Mesenchymal cells which arise from bone marrow stroma
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− | • Produce bone matrix = osteoid
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− | • Cell membranes are rich in alkaline phosphatase (ALP)
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− | Osteocytes
| + | *'''Cells''' |
− | • Osteoblasts that have become surrounded by mineralised bone matrix
| + | **'''Osteoblasts''' |
− | • Occupy cavities called lacunae
| + | ***Mesenchymal cells |
| + | ***Arise from bone marrow stroma |
| + | ***Produce bone matrix = '''osteoid''' |
| + | ***Cell membranes are rich in alkaline phosphatase (ALP) |
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− | Osteoclasts
| + | **'''Osteocytes''' |
− | • Multinucleated cells derived from haematopoietic stem cells
| + | ***Osteoblasts that have become surrounded by mineralised bone matrix |
− | • Responsible for bone resorption (have a brush border for this)
| + | ***Occupy cavities called '''lacunae''' |
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− | Matrix
| + | **'''Osteoclasts''' |
− | • Type I collagen forms the backbone of the matrix
| + | ***Multinucleated cells |
− | • Mineral – accounts for 65% of bone and includes Ca, P, Mg, Mn, Zn, Cu, Na
| + | ***Derived from haematopoietic stem cells |
| + | ***Responsible for bone resorption (have a brush border for this) |
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− | Bone organisation | + | |
| + | *'''Matrix''' |
| + | **Type I collagen forms the backbone of the matrix |
| + | **Mineral – accounts for 65% of bone and includes Ca, P, Mg, Mn, Zn, Cu, Na |
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| + | ===Bone organisation=== |
| Osteoblasts deposit collagen in different patterns | | Osteoblasts deposit collagen in different patterns |
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