TOB CL6 Ossification Flashcards
1
Q
Osteoprogenitor Cells (5)
A
- derived from mesenchymal stem cells
- resting cells
- form osteoblasts
- lie in innermost layer periosteum and endosteum
- found in normal growth & bone remodeling
2
Q
Osteoblasts (4)
A
- differentiated to become osteocyte
- lower columnar cells
- secrete collagen & ground substances
- involve in calcification of matrix
3
Q
Osteocytes (5)
A
- mature bones cells, oval
- lie in lacuna
- surrounded by bone matrix
- maintain surrounding matrix
- has cytoplasmic process in canaliculi
4
Q
Osteoclasts (4)
A
- large multinucleated cells
- derived from monocytes-macrophages cell line
- resorp bones
5
Q
Classification of Bones
Shapes ( 4) and explain
A
- long
- length > thickness
- Tubular shape - marrow cavity
- long bone except clavicle - endochondral ossification - short
- cuboidal ( length = thickness )
- spongy bone & marrow
- enclosed by thin layer of compact bone
- e.g. carpal & tarsal - Flat
- spongy bone & marrow
- e.g. scapula & skull - Irregular
- irregular shape ( x fit any of the above )
- vertebrae, hip bone
6
Q
Classification of Bones
Region (2)
A
- axial
- central axis - appendicular
- appended to the central axis
7
Q
Classification of Bones
Structure (2)
A
- Compact
- hard, dense
- shaft of long bone - Spongy
- trabecular with intercommunicating spaces
- end of long bone
8
Q
Classification of Bones
Others (3)
A
- Sesomoids bones
- Nodules in tendons
- expose to friction or pressure
- e.g. patella - Pneumotic bones
- with air cavities - light weight
- evagination of mucous lining of nasal cavities , ear canal
- maxilla ( mostly facial bones ) - Accesory bones
- x regularly present
9
Q
Classification of Bones
development (2)
A
- Intramembranous ossification
- flat bones - Endochondral ossification
- long and short bones except clavicle
10
Q
What is ossification ? (2)
A
- site of bone formation
- from center to end
11
Q
Primary ossification center
1. where
2. when
A
- diaphysis, shaft of long bone
- prenatal
12
Q
Secondary ossification center
When (2)
A
- later than primary except lower femur - can determine baby’s age
- postnatal ( after birth )
13
Q
Intramembranous ossification 3 concept
A
- mesenchymal cell > bone
- no hyaline cartilage model
- forming between high vascularized connective tissue
14
Q
Process of intramembranous ossification
A
- mesenchymal cells - migrate & aggregate in specific are - differentiate into capillaries, osteogenic cells (osteoprogenitor) - osteoblasts - highly vascularized & undergo hypertrophy - cell more vascularized - larger and rounded - cluster - ossification center
- osteoblasts secretes osteoids ( uncalcified bone matrix / contains type I collagen + proteogylcans ) - secrete alkaline phosphatase & Ca containing vacuole - calcify - trapped - osteoids in lacuna
- newly bone matrix > bony spicules - mesenchymal cell near bony spicules proliferate - osteoblasts - produce new matrix - bony spicules enlarge & combine tgt - form trabecular network - immature bone ( Woven bone ) - rearrange - mature lamellar bone
trabecular network - blood vessels & hematopoietic cells invade into the intercommunicating spaces - red marrow
- periosteum secrete compact bone which is superficial to the spongy bone ( trabecular bone )
15
Q
Endochondral ossification process
A
- mesenchymal cells - differentiate to become chondrocytes - form hyaline cartilage model (type II collagen + ground substances) - interstitial growth & appositional growth - chondrocytes
- hydrotrophy - compress surrounding cartilage matrix - alter the content by adding substances into it - calcifies - impermeable to oxygen and nutrients - chondrocytes dies ( apoptosis) - leaving empty spaces - trabeculae-shaped calcified cartilage
- osteoclasts form spaces in collar bone - allow osteogenic buds (blood vessels, ostegenic cells & hematopoetic cells) reach the apoptosis area - osteogenitor differentiate - osteoblasts - osteoids - calcify - bone development area - later on producing calcified bone complex ( primary ossification center ) - osteoclasts removes the calcified cartilage plate - medullary / marrow cavity where lacunae combines - osteogenic bud invade - bone marrow
- osteoblasts lay down around medulla cavity - thickening of bone - appositional growth - replace cartilage with bone
- after birth - secondary ossification center in epiphysis - similar process as primary EXCEPT spongy bones remains - no medullary cavity
completed - hyaline cartilage replaced by bone EXCEPT articular cartilage ( remains on the surface of epiphysis ) & epiphysis plate ( in metaphyseal region )
