5.4: Injury and healing (part 1 of 2) Flashcards
3 mechanisms of bone fracture
Trauma
Stress
Pathological
What 2 things are bones made up of
Cells
Matrix
How do bones develop in utero
Intramembranous (flat bones e.g. skill, clavicle, mandible) and
endochondral (long bones, ribs, vertebrae)
ossification
Process of Intramembranous ossification
Mesenchymal cells condensate, differentiate into osteoblasts and secrete osteoid
This traps osteoblasts which become osteocytes - collate and form ossification centre
Multiple ossification centres form and fuse, forming trabecular matrix and periosteum
Compact bone develops
Intramembranous ossification is
Bone development from fibrous membranes
Process of endochondral ossification
Bone collar formation
Cavitation
Periostea’s bud invasion
Diaphysis elongation
Epiphyseal ossification
Which bone formation takes a longer amount of time?
Endochondral ossification
Primary ossification centre of endochondral ossification
Diaphysis
What is the secondary ossification centre of endochondral ossification
Epiphysis
2 Different types of bone structure
Immature bone
Mature bone
Characteristics of immature bone
First bone that’s produced
Laid down in a woven manner - relatively weak
Mineralised and replaced by mature bone
Characteristics of mature bone
Mineralised woven bone
Lamellar structure - relatively strong
2 types of mature bone
Cortical
Cancellous
Characteristics of cortical bones
Compact - dense
Suitable for weight bearing
Characteristics of cancellous bone
Spongy - honeycomb structure
Not suitable for weight bearing
Organisation of cortical bone (compact)
Osteons found in compact bone, repeated structural units , around central Haversian canal which contains blood vessels, nerves and lymphatics
Structure of long bones
Diaphysis - long part of bone
Metaphysis- area that flares up
Physis- growth plate
Piphysis - distal or proximal part of bone
2 locations of Osteogenic cells
Marrow
Deep layers of periosteum
Where are osteoblasts found
Growth portions of bone :
Periosteum and endosteum
Where are osteoclasts formed
Bone surfaces and at sites of old, injured or unneeded bone
Where are osteocytes found
Entrapped in matrix
2 ways that bones can grow
Interstitial - increased length
Appositionsl -increased thickness and diameter
Where does Interstitial occur
In the physis
Where does appositional growth occur
Periosteum :
Osteoblasts add more and more bone cells
Role of bone in calcium homeostasis
Calcium hydroxyapatite- structural support
Calcium deposited and withdrawn during bone remodelling
Regulated by PTH and calcitriol
Calcitonin stimulates calcium uptake into bone
VitaminD helps body absorb and use calcium
Trauma causing bone to break
Low energy or high energy transfer
Stress fracture is
Abnormal stress on normal bone