bone function and repair Flashcards
what are the main functions of bone
mechanical
synthetic- haempoiesis
metabolic- mineral storage/ fat storage and acid base homeostasis
Explain intra-membranous ossification
MSC aggregate and differentiate to osteoblasts
bond expands as series of spicules
spicules interconnect to create cancellous bone
remodelling allows compact bone formation
Describe the structure of compact bone
arranged in osteons concentric rings of lamellae around central harvesian canal
volkmann canals perforate
periosteum outside surface
endosteum line medullary cavity
what is the endosteum
lining of medullary cavity
inside surface of cortical bone
what is the periosteum
external surface of cortical bone
describe the structure of cancellous bone
porous structure made up of trabeculae
no harvesian or volkmann canals
surrounded by BM
how does bone resist fracture
puts down collagen in direction of force to provide strength
mainly resists through cortical bone lamellae can slip relative to each other providing resistance
name some factors affecting bone stability
exercise-remodelling
oestrogen and androgen
vit D /C/ K/ B12
thyroid and parathyroid hormones
Explain the process of fracture repair
haematoma forms as BV broken
swelling and inflammation granulocytes enter
new bv infiltrate haemotoma - granulation tissue forms
fibroblast and chondroblasts active to fibrocartilaginous callus form with developing trabeculae
trabeculalr develop and endochondral and intramembranous ossification occur forming bony callus
bone remodelling to original structure
What are the two step in bone reabsorption
osteoclasts make wide tunnel in bine called cutting cone
osteoblasts make smaller tunnel of cortical bone- closing cone
Harvesian canal created
What is osteogenesis imperfecta
COL1A mutation so collagen 1 not correctly produced
weak bones and increased fracture risk
short stature and height
what is rickets
children vit d deficiency resulting in poor mobilisation of Ca and mineralisation of bone weak bones and short height/ stature pain to walk bowed legs
what is osteomalacia
rickets in adults usually due to malnutrition kideny diseases surgery drugs protection form sunlight
what is osteoporosis
a disease where there are microarchitectural changes in bone characterised reduced bone mass/density
incomplete filling of osteoclast resorption bays
What are the types of primary osteoporosis
type 1- postmenopausal women
type 2- senile osteoporosis
