week 3- lesson 2 Bone Flashcards
What is the function of the trabecular in a normal bone like the femur
-allow dissipation/spreading out of forces across a large surface area, or towards the more dense areas of compact bone
-acts like shock absorber to resist forces
-align along lines of stress where forces are greatest
What is the function of cortical bone in a normal bone like the femur
Allow the dissipation/spreading out of forces vertically to and from spongy bone
What is the lamellar
Concentric rings/layers of the osteon
What is the lacunae
Sites of osteocytes
What is the Haversian canal
Blood vesssles travel through each osteon in canals. Vertical canals are knows as Haversian canal
What do osteoblasts do
Build new home, produce and deposit osteoid which become calcified once deposited
What do osteoclasts do
Breakdown bone. Secrete enzymes and acids to dissolve bone to release minerals or release minerals or remodel newly formed bone
What is an osteocyte. What do they do
Mature osteoblasts. Some osteoblasts entomb themselves during the building process. Osteocytes can revert back to osteoblasts if required. In their entombed state osteocytes monitor stress in the fluid in the cuniculi and lacuna that they occupy. They help to signal new bone growth.
What is a bone remodelling unit (BMU)
Area of the bone that is being remodelled and includes the old and new bone material and the group of cells involved in the process
Which cells is stimulated in the remodelling phase
Osteocyte by stress/load
Using Wolfs law, explain why the highest bone mineral density is seen in high impact activities and lowest in low impact sports
Bone adapts to loads under which it is placed. High impact activities such as basketball load the skeletal compared to swimming where there’s no gravitational impact. In response to high loading, osteoblasts dominate and bones become stronger
Why would people’s diet affect their bone health in their older years
Up until mid 20’s we are able to deposit calcium into hydroxyapatite into our bone stores. We can stil pay into ‘Bank of Bone’ this is the store of bone tissue (and calcium ions) we have for the remainder of our lifespan. A diet which restricts dairy and protein through childhood and young adulthood will result in a reduced deposit of calcium in our bones.
Describe how the epiphyses plate normally develops out of a cartilage model
The proliferating cartilage zone is where the chondrocyted are continuously dividing which creates new layers of chondrocytes
Older chondrocytes at the base of this zone eventually become too far from the proliferating zone and the good blood supply it has. They begin to enlarge (HYPERTROPHIC ZONE)
Enlarging cells move further towards the centre of the growing bone
They eventually drop into calcified zone where they begin to calcify and harden their cartilage matrix then they die away. (OSSIFICATION LAYER)
This ossified tissue is replaced by spongy bone produced by the approaching osteoblasts ( OSTEOGENESIS)
Overall, idea is that the chondrocytes are growing away at the proliferating zone and elongating the vibe whoost the osteoblasts are replacing the matrix they produce with spongy bone
In bone how will there be areas of weakness
There will be fewer trabeculae.
Predispose bones to fracturess
State the 5 functions of bone tissue
-light weight to allow movement
-stiff to provide rigidly for leverage
-flexible to absorb energy
-strong to resist external force
-production of blood cells in the bone marrow
