Development and growth of Bones Flashcards
What important mechanical properties do bones have?
Cable like flexibility+resistance to tension =because of collagen
AND
Pillar like stiffness+resistance = because of collagen complex with HA/Ca
What two types of bone tissue exist?
Immature/Woven bone (in adults only when repairing/disease)
Developed/Lamellar (layers) bone
What are other names for head and shaft of the bone? what are other (very broad overview) of bones?
Head-epiphysis, Shaft-diaphysis Compact outside-cortical Spongy inside-cancellous Medullary cavity in diaphysis Numerous small holes for blood supply
How is lamellar bone arranged? Why?
Outer layer of compact lamellar bone-Cortical
Inner layers of interlacing struts of lamellar bone-cancellous bone (or spongy, or trabecular) (BUT NOT WOVEN OK)-still lamellar, but less dense
Makes the bones lighter + space for marrow
What are osteons?
Concentric lamellar arrangements of cortical bone that surround a blood/lymph supply-forms a column
Pretty much a UNIT OF BONE -all bones are made from this unit
How is the blood supply of bones organised?
Mainly Nutrient arteries that pass via nutrient canals that enter the medullary cavity and spread from there
But also has a large exterior capillary supply
What is the Periosteum?
Fibrious and cellular layer that sits on surface of bone
Cells are important for growth and repair
Large vascular network, and large nerve supply (where pain comes when bone damaged)
What are the 3 main cells found in bone?
Osteogenics stem cells form osteoblasts and osteocytes
Also have osteoclasts
Osteoblast-forms the bone matrix
Osteocytes-sit in bone and maintain it
Osteoclasts-Resorb/breakdown of bone matrix
When do bones start to develop? when do they end? What two types of ossifications happenn
Skeleton starts to form at 6 weeks and end at 25
Intramembranous-in existing vascular tissue, where bone matri deposits on collage, then mineralised and remodels
-Usually to form flat bones
Endochondral-withing exiting foetal cartilage models-cartilage calcifies. Osteoclasts cut channels into it for vessels, and osteoblasts come with to remodel =>this is because bones need to support weight while growing/remodelling (this leads to shaft ossify 1st, then epiphysis-with a growth plate between/epiphyseal plates)
How adaptable is bone?
Can growth without compromising support functions
Increase/Decrease density in response of pattern of use
Can alter its shape in reponse to pattern of use
Can repair when fractured
What are the important factors to bone in remodelling? How about healing?
Large blood supply necessary
Osteocytes maintain matrix, but can be activated to becomes osteoblasts
Osteoclasts important to clear debris and damaged parts
Healing also requires large blood supply-hematoma is important process->then callus formation arround (connective tissue), then woven bone, finally remodel and
What is apposition?
Additions to exterior of periosterum-external osteocytes are activated to become osteonlasts and produces new bones, which create ridges, and surround blood vessels forming osteons.
