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Wht are 5 functions of the skeletal system
Energy Storage (yellow marrow)
Production (blood cells)
Storage (Calcium & Phosphate)
Support & protection of tissues
What is hemopoisesis
blood cell production occurs in red marrow
What lines the outer bone? what lines the marrow?
What are the shafts of the long bone called? the heads?
What are the 4 types of bone cells
osteocytes, osteoblast, osteoprogenator, Osteoclast
What cells form osteoblast? Where are these found?
Osteoproginitor cells–found in inner layer of periosteum and endosteum
What is an Osteon(lamellae)
• is concentric rings of calcified matrix surrounding a vertically oriented blood vessel
Where are osteocytes found in compact bone? How do they communicate?
In spaces called lucunae..communicate through canaliculi filled with extracellular fluid that connect one cell to the next cell
What and where is trabeculae found?
•Latticework of thin plates of bone oriented along lines of stress
found on the ends of long bone
Are osteons in the trabecule of spongy bone?
Intramembranous bone formation
formation of bone directly from mesenchymal cells
•Endochondral ossification =
formation of bone within hyaline cartilage.
What cell begins Intramembranous Bone Formation
what is the process of intramembranous bone formation?
•Osteoblasts surround themselves with matrix to become osteocytes. •Matrix calcifies into trabeculae
•Mesenchyme condenses as periosteum
•Superficial layers of spongy bone are replaced with compact bone.
Periosteumn 2 layers?
–fibrous layer = dense irregular CT –osteogenic layer = bone cells & blood vessels that nourish or help with repairs
Steps to Endochondral Bone Formation
1. Mesenchymal cells form cartilage model
2.Model Grows (middle calcifies)
3. Development of the primary ossification center (osteoblast form trabeculae/ osteoclast form medullary cavity)
-campact bone moves to side and spongy bone is broken down.
4.Development of 2nd oss. center (blood vesles enter the epiphyses, spongy bone is formed but no medullary cavity)
Articular cartilage stays
What is the process of epiphyseal plate growth
cartilage cells are produced by mitosis on epiphyseal side of plate..cartilage cells are destroyed and replaced by bone on diaphysel side
At what ages do epiphyseal plate close? At what age does growth in lenghth stop?
18 to 25
stops at 25
What cause the cartilage model to grow during endochondral bone formation?
in length (interstitial) by chondrocyte division and matric formation
in width (appositional)by formation of new matrix on the periphery by new chondoblast
What are the 4 zones of epiphyseal plate growth
z of resting cartilage (anchors growth plate to bone)
z of proliferating (rapid cell division)
z of hypertrophic(cells enlarged & remain columns)
z of calcified cartilage*thin zone cells mosty dead
Bone growth in width process..
•Periosteal cells differentiate into osteoblasts tunnel around periosteal blood vessel. •Concentric lamellae fill in the tunnel to form an osteon.
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