Bone Remodelling Flashcards
What part of the bone is in charge of longitudinal bone growth
Epiphyseal plate
What are the 3 cell types in bone
Osteoblasts
Osteoclasts
Osteocytes
What happens in endochrodal ossification
Chondrocytes die in the calcified matrix
Function of osteoblasts
Build new bone
How do osteoblasts build new bone
By producing and depositing osteopenia which then becomes calcified
Function of osteoclasts
Breakdown bone
How do osteoclasts break down bone
Secreting enzymes and acids tear dissolve bone
What is a mature osteoblast called
Osteocyte
True or false- osteocytes can revert back to osteoblasts
True
Function of osteocytes
Monitor stress in the fluid in the cuniculi and lacuna as they help signal new bone growth
Function of trabeculae in a normal bone
Allows spreading out of forces across a large surface area as it acts a shock absorber, they align along lines of stress where the force is the greatest
Function of cortical bone in a normal bone
Allows spread out of forces vertically to and from spongy bone
What are lamellae
Concentric rings on the osteon
What is lacunae
Sites of osteocytes
What is a Haversian canal
Where blood vessels travel through each osteon in canals (vertical)
Two main cells in bone remodelling
Osteoblasts and osteoclasts
Which cell is stimulated in the first remodelling stage (activation)
Osteocytes
List stimulations of the activation stage
Stress/load/exercise
Signalling - hormone, growth factors
Injury / inflammation
Aging
What happens to osteoclasts in the reabsorption phase
Begin to release acid and enzymes and starts to break down the bone
Which of the cells complete the remodelling
Osteoblasts
Which cell type is mainly involved in lengthening bone within the epiphyseal plate
Chondrocytes
What happens in the proliferative zone
Cells are replicating
Compare the proliferation zone and hypertrophic, what happens to cell structure
Cells enlarge, as chondrocytes move further away from epiphyseal edge, diffusion of nutrients is reduces and chondrocytes enlarge
What is happening to cells in the hypertrophic zone treat explains spongy bone formation
Cells enlarge they begin to calcify and eventually die. Osteoblasts from metaphysical convert the calcified material into spongy
What is wolfs law
Bone adapts to the load it is placed under
Explain the arrangement in trabeculae in compressed femur
Tension forces push down on the head and compression forces come up the femur
What is tension forces
Body weight pushing down on the head of femur
What is compression forces
Impact / ground reaction forces coming up the femur during walking etc
What is wards triangle
An area of weakness as there is less trabeculae
How can wards triangle predispose rather bone to fractiure
It predisposes bone to fracture at the weak point especially to lateral forces which occur during a fall
Why is the highest bone mineral density seen in high impact activities and low in low impact
Bone adapts to loads under it is placed, high impact actives creates high loading and this is where osteoblasts dominate and bones become stronger
