lecture 11 Osteogenesis and joints Flashcards
What are the steps of intramembrane bone formation? (starting w/ mesenchyme)
- Aggregation of mesenchymal cells
- controlled by: Wnt, Hedgehog, FGF, TGF-beta
- Mesenchymal -> Osteoblasts
- Osteoblasts secrete osteoid trapping some of he osteoblasrs = blastema
- Trapped osteo blasts -> osteocytes
- Osteocytes form a functional syncytium
- Mineralization (via Ca ions)
- Osteoblasts covering primary bone tissue and secrete more osteoid on the surface
- Osteoid includes collagen 1 and non-collagen proteins
- Primary ossification center becomes a trabecula
- Numerous trabeculae fuse tofgether to form spongy bone
What are the steps of intramembraneous bone formation? (starting with woven)
- Woven bone
- collagen fibers are arranged randomly
- collagen fibers become aligned
- bones become lamellar
- lamellae may become symmetrically arranged around a blood vessel forming an osteon (haversian system)
- membrane bone usually consists of two layers of compact bone enclosing a layer of spongey bone (DIPOLE)
True or False, Intramembraneous formation (bone) does not include cartilage
TRUE
WHat are the steps of endochondral bone formation?
Cartilage i replaced by bone
- primary ossification center occurs in future diaphysis of cartilage model
- chondrocytes become hypertrophic
- chondrocytes secrete vascular endothelial growth factor
- Blood vessels break through perichondrium, bringing osteoprogenitor cells,
- hypertrophic cartilage cells undergo apoptosis leaving behind thin strands calcified matrix.
- osteoblasts use calcified strands as substracts for deposition of osteoid
- osteoid is calcified
know this pictures
know this photo
What is the osteoclastic chase and the chondrocytic run?
Itis the process of the osteoclasts invading and replacing chondrocytes. the chondrocytes are runing away from the ossification front
or
you could say the ephiesis plate is moving as the osteoclasts are chasing it/
What is bone remodeling?
HE SKIPPED THIS LO IN LECTURE
4 steps
- activation
- O. clasts precursors are recruited to haversian canal and become O clasts
- line bone lamella facing canal and start resorption
- resoprtion
- recruits more O clasts precursors
- O blasts appear
- reversal
- resverse the resporption progress (by reorganizng and secrete osteon. creating new organized lamella
- formation
- continue to lay down osteon until they are trapped in matrix and become O. Cytes.
- NEw osteon or haversian system is formed leaving behind interstsitial lamellae
What is a joint?
where two bones come together
What are the three different kinds of joints?
Cartilaginous( amphiarthroses)
Fibrous Cartilage (synarthosis)
Synovial (diarthoses)
How are cartilaginous joints classfied?
- Synchondrosis
- Hyaline cartilage
- epiphyseal plate, first sternocostal joint
- Symphyses
- Fibrocartilage
- intervertebral discs and symphyses
How are fibrous joints classified ( synarthroses)?
- by collagenous or elastic fibrous tissue
- Suture
- joints b/w bones of calveria
- Gomphosis
- peg in the socket joint of teeth alveoli
- Syndesmosis
- bones are joined by an interosseous fibours membrane such as the fibrous membrane b/w tibia and fibula
What are synovial joints classified? (diarthosis)
- movable joints exemplified by connective capsule surrounding a fluid filled joint space
- synovial joints are often reinforced by thickens of the outer parts (ligaments)
- stabilize capsule and joint
- control restrIct direction and range of motion
What are the different types of synovial joints and examples of them?
based on how many planes of movement
- monoaxial: 1
- hinge: elbox and knee
- Pivot: alantoaxial or radiounlnar
- biaxial: 2
- Condyloid: First metacarpophalangeal and atlanto occipital joints
- Saddle: first carpmetacarpal
- Triaxial: 3
- ball n socket : glenohumeral, femoroactabular joints
What are the charcteristics of articular cartilege?
hyaline cartilege
lacks perichondrium
not lined by synovial membrane
