MICROANATOMY Blk1
Terms
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- Process of INTRAMEMBRANOUS OSSIFICATION
- (1) Condensation of Mesenchyme and Vascularization (2) Differentiation of Mesenchymal cells into Osteoprogenitor cells into Osteoblasts (3) Osteoblast lay down Osteoid --> Spicules of Woven Bone formed (4) Osteoblasts turn into Osteocytes when surrounded by Bone Matrix (5) Mesenchyme proliferate and continue to form osteoblasts (6) Bone spicules increase in size (7) Osteoclasts remove Woven bone and replaced with Lamellar Bone
- Process of ENDOCHONDRAL OSSIFICATION
- (1) Mesenchymal cells differentiate into CHONDROBLASTS, secrete hyaline cartilage (2) Signaling induces HYPERTROPHY of chondrocytes and produce Type X Collagen (3) Hypertrophic cells induce perichondrium to differentiate into OSTEOBLASTS (4) Osteoblasts form ring of bone around diaphysis = BONY COLLAR (5) Hypertrophic cells die and surrounding cartilage matrix CALCIFIES (6) OSTEOGENIC BUD enters empty spaces where chondrocytes were (7) Osteoprogenitor cells differentiate into Osteoblasts and deposit bone = MIXED SPICULES (8) Osteroclasts differentiate from osteoprogenitor cells and remove bone (9) ZONE OF OSSIFICATION continues to grow proximally and distally (10) Mixed Spicules replace wIth LAMELLAR BONE
- Part of Growth Plate that maintains bone growth longitudinally
- Zone of Reserve Cartilage
- Part of Growth Plate responsible for actual growth of bone
- Zone of Proliferation
- Zones of Growth Plate
- (1) Reserve Cartilage (2) Proliferation (3) Hypertrophic (4) Calcification (5) Ossification
- 2 Types of Cells in Synovial Membrane. Fxn?
- (1) Type A - phagocytic, remove debris from synovial space (2) Type B - fibroblast-like, secrete synovial fluid
- Process of INTRACORTICAL REMODELING
- (1) CUTTING CONE made by Osteoclasts (aka RESORPTION CANAL) (2) OSTEOBLAST fill space around centrally growing b.v. (3) Concentric circles form outside inward and central vascular channel narrows. Haversian system complete.
- What is the bone remodeling process sensitive to?
- (1) LOCAL mechanical stress (2) SYSTEMIC effects of overall activity levels
- Resorption process inhibited by what hormone?
- CALCITONIN
- Resorption process stimulated by what hormone? How?
- PTH High PTH --> Binds to PTHR on OSTEOBLASTS --> Release MCSF & RANKL --> stimulate OSTEOCLAST MATURATION
- Result of LOW PTH levels in bone cell activity
- LOW PTH --> OSTEOBLASTS secret OSTEOPROTEGERIN --> Binds to RANKL --> INHIBIT differentiation of OSTEOCLAST
- High Estrogen affects in Bone cell activity
- High ESTROGEN --> Increase OSTEOPROTEGERIN --> Bind to RANKL --> INCREASE OSTEOBLAST LIFE
- Growth Factor secreted by MATURE CHONDROCYTES that help promote CELL PROLIFERATION
- Ihh = Indian Hedgehog
- Growth Factor secreted by MATURE CHONDROCYTES that help INHIBIT CELL PROLIFERATION
- PTHrp = PTH related peptide *Indirectly released by Ihh to prevent over proliferation of chondrocytes
- Some people are short due to genetic mutations in what growth factors that affect chondrocyte growth
- (1) Ihh (2) PTHrp