Osteogenesis Flashcards
Two types of cone
compact and spongy
location of compact bone
bone surgace
compact bone contains a very dense matrix composed of
lammellae plates
3 types of compact bone lamellae
1) circumferential: encircle the inner and outer surface of diaphysis
2) concentric lamellae: osteocytes in their lacunae arranged in rings
3) interstitial lamellae: remenants of the old haversian systems resulting from bone remodelling.
in compact bone, osteocytes are located in the dense ___, found in lacunae cavities arranged in ____ ___
in compact bone, osteocytes are located in the dense MATRIC, found in lacunae cavities arranged in CONCENTRIC LAMELLAE
osteocytes in the dense matrix of compact bone are supplied by blood vessel and nerves that travel through ____> 2 types.
Canals.
1) volkman canals: penetrate the SURFACE and connecets haversian canals
2) haversian canals: run parallel to the surface.
Structural unit of compact bone. Components
a haversian system/osteon
involves 1) haversian canal that houses the blood and nerve supply
2) concentric lamellae: osteocytes in their lacunae arranged in rings.
function of canalculi
cellular connections between osteoctes. allows for diffusion of nutrients from cell to cell towards the periphery of haversian system.
location of spongy bone
interior of bone
purpose of trabeculae
delicate network of bone for strengthening purposes.
trabeculae is surrounding by
mesenchyme
diploe
internal spongy bones.
2 methods of ossification
1) endochondral ossification
2) intramembranous ossification
endochondral ossification occurs
in long bones and at the epiphyseal plate
6 zones of the epiphyseal plate
1) zone 1: resting cartilage: resting hyaline cart
2) zone 2: zone of proliferation. CHONDROCYTES multiply. form lines of lacunae (aggregates)
3) zone of hypertrophy. Lacunae grow.
4) zone of calcification. Becomes more basophillic.lacunae mesh together. Kind of hard to tell between zone 3 and 4.
5) zone of ossification. Chondrocytes die and bone is deposited.
6) zone of erosion: osteoclasts make marrow canals from newly deposited bone
the beginning of endochondral ossification occurs in hyaline cartilage at the ____ ___ of ossification in the ____
the beginning of endochondral ossification occurs in hyaline cartilage at the PRIMARY CENTER of ossification in the DIAPHYSIS (in embryo)
endocondral ossification: at the primary center of ossification, osteoblasts develop from ____ and begin to:
What happens to perichondrium?
osteoblasts begin to develop from MESENCHYMAL cells and begin to deposit a ring of periosteal bone for support as the internal cartilage gets erodid. the perichondrium of the cartilage becomes periosteum.
after a boney collar is formed by original osteoblasts, outline the rest of the steps of endochonrdral ossification (DURING EMBRYO)
1) chondrocytes begin multiplying and enlarging. calciufication also occurs.
2) periosteal buds grow to form blood vessels that branch into enlarged lacunae that was formed during hypertrophy
3) ossification continues to occur because mesenchymal cells migrate into the cavities and differentiate into osteoprogenitor cells in the marrow spaces. Ops differentiate into osteoblasts, that can deposit collagenous osteoid and then bone into the remaining cartilagenous fragments.
4) hemopoietic stem cells also enter and begin producing marrow
5) after ossification, osteoclasts move in and resorb bone to form marrow cavities.
After birth, what are the last stages of endochondral ossification
6) bone continues to grow except at articular cartilage or epiphyseal plates
7) all bone intially forms as woven bone, so it must be remodelled at the surface to form compact bone
8) secondary ossification centers form. They are separated by the primary center of ossification by the epiphyseal plate.
- allows for the deposition of bone at the EPIPHYS (tips of long bone). Epiphyseal plate and articular cartilage is left for growth spurts.
9) after growth is completed, the epiphyseal plate itself ossifies and an adult is left with the epiphyseal line.
the primary and secondary center of ossification is separated by the
epiphyseal plate
what is intramembranous ossification? what does it produce?
bone forms within mesenchymal membrane. produces flat bones of the skull.
process of intramembranous ossification
1) mesenchymal cells differentiate into osteoblasts.
2) osteoblasts produce and deposit osteoid
3) osteoid becomes mineralized
4) osteoid becomes trabeculae, and fuse with one another to form spongy bone
4) bone marrow develops into spaces of the trabeculae
5) mesenchyme at the periphery of the bone CONDENSES to form periosteum and enosteum.
6) surface of the woven bone are remodelled to form compact bone.
in flat bones of the skull, the layers on the surfaces are called ___ and ___ ___s, and are separated by ____.
in flat bones of the skull, the layers on the surfaces are called INNER and OUTER TABLESs, and are separated by DIPLOE: spongy bone between compact bone tables.
in endochondral ossification, the osteoblasts form periosteal bone bony collar using the process of :
intramembranous ossification (osteoblasts–> osteoid –> mineralization –> bony collar)
