Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
|
Cortical/Compact Bone
properties? % calicified? fxn? |
Dense,
90% calicified Mechanical/protective |
|
|
Trabecular/cancelous bone
properties? % calicified? fxn? |
thin
15-20% calcified endosteal bone surface - bone-soft tissue metabolic fxn, contains stem cells |
|
|
Cells in bone
|
Osteoblast
Osteoclast Osteocytes Osteoprogenitor Bone Marrow |
|
|
Osteoblast
|
bone fomring mononuclear from stromal
|
|
|
Osteoclast
|
bone resorbing, multinuclear, from hemopoietic stem cells
|
|
|
Osteocytes
|
mechanoreceptors in bone-canaliculi allow cell-cell comunication
|
|
|
Mesechymal Stem Cells
|
ECM signal--> fibroblast-->osteoblasts etc. etc.
|
|
|
Compare Contrast baisc phases of intramembranous/endochondral bone formation
|
intramembranous bone formation involves the radiating ossification of mesenchymal condensation in flat bones such as cranium maxilla, mandible
Endochondral: cartilaginous precursuors in long bones(mandibule, cranial base) |
|
|
Growth Zone
|
-Eiphyseal/growth =hyaline cartilage plate found at each end of long bones.-->allows longitudinal growth of bones
-chondrocytes underogoing constant division via mitosis so that daughter cells stack facing epiphysis while older pushed towards diaphysis. -as older chondrocytes degenerate, osteoblast ossify remains to from new bone |
|
|
Inactive Zone
|
Epiphyseal End
|
|
|
Hypertrophic zones
|
proliferative found distally ending with band of ossifying cartlage called metaphysis
|
|
|
Resting Zone
|
Germinal Layer supplies developing cartilage cells, injury = stop growth
|
|
|
Proliferative Zone
|
Where bone length is created via active growth. Chondrocytes flattened and divide/organize into columns
no cell division, but chondrocytes differentiate |
|
|
Metaphysic
|
dead chondrocytes calcify, template for osteoblastic bone formation
|
|
|
Zones of growth plate
|
Epiphyseal growth plate
Resting Zone Hypertrophic Resting Zone Proliferative Hypertrophic Metaphysic |
|
|
Describe cycle of bone remodeling's importance in bone homeostasis
|
1. Constantly regrowing/modeling due to microscopic cracks via mechanical forces.
2. Remodeling Units: osteoclast/blasts |
|
|
Describe Bone Remodeling Cycle(1-6)
|
1. Embedded osteocytes secerte sclerostin, which inhbits Wnt signaling in cells near surface
2. Osteocytes detect crack, screte factors(prostaglandins, nitric oxide) and undergo apoptosis 3. Lining cells pull away from bone matrix, form canopy merging w/ blood vessels 4. Stromal Cells released from sclerostin inhibition, exposed to interlukin-1 5. Stromal Cells-->preosteoblasts + secrete macrophage colony stim. factor-->more pre-osteoblasts 6. Preosteoblast proliferate and secerte Wnt, interleukins. |
|
|
Describe Bone Remodeling Cycle(7-11)
|
7. Preosteoblasts express RANK-L, pre-osteoclast have RANK receptors
8. Preosteoclast enlarge and fuse with mature osteoclasts. 9. Osteoclasts bind bone matrix via integrins, secrete acid + cathepsin K to resorb bone 10. Bone-growth factors IGF, TFG-beta released 11. Osteoclast undergo apoptosis 12.Preosteoblasts mature into osteoblasts-->no more RANK-L, osteoprotegerin secerted instead 13. Osteoprotegerin inhibits RANK L and thus activation of pre-osteoclasts |
|
|
Describe Bone Remodeling Cycle(12-)
|
14. Pre-osteoblasts proliferate and then mature into osteoblast which secrete osteoid and minerealize it to fill cavity
14. Some osteoblast turn into osteocytes while rest apoptosis 15. Canopy dies |
|
|
Bone Stims
|
IL-1alpha and beta
|
|
|
Bone inhibitors
|
Calcitonin, bisphosphonates
|
