bone function and repair Flashcards
Function of bone
Mechanical- protect important and delicate tissues and organs, provide a frame work for the overall shape of the human body, from the basis of levers involved in movement
Synthetic- haemopoiesis(holds and projects red bone marrow)
Metabolic- mineral storage (calcium and phosphorus)
fat storage yellow bone marrow
acid-base homeostasis (absorbs and releases alkali salts to help regulate blood pH)
Intramembranous ossification has how
Formation of bone from the cluster of mesenchymal stem cells in center of bone (not the replacement of hyaline cartilage)
What kind of bones do intramembranous ossification
Flat bones formation and the thickening of long bones
Stage I of into membranous ossification
Mesenchymal cells form a tight cluster
MSC transform into osteoprogenitor cells and then into osteoblasts
osteoblasts laydown a osteoid (ECM cotaining type I collagen)
Stage II of intramembranous ossification
Osteoid mineralises to form spicules (surrounded by osteoblasts and containing osteosytes)
stage III of intramembranous ossification
spicules join to form trabeculae
trabecule merge to form woven bone
stage 4 of intramembranous ossifcation
trabeculae replaced by the lamella of mature compact bone
ECM contains what type of collagen
type I
does cancellous bone contain Haversian and Volkmanns canals
No
explain the osteocyte arrangement in immature and mature bone
immature bone has osteocytes in random arrangements
mature bone has osteocytes arranged in concentric lamellae of osteons
bone strength
bone resist fracture - great tensile and compressive strength and a degree of flexibility
main frrce lines are through the cortical bone
why are the main force lines through the cortical bone
lamellae are thought to be able to slip, relative to each other to resist fracture
factors affecting bone stability
osteocyte have both osteoclast and osteoblast activity
activity of osteoblast
activity of osteoclast
4 stages of fracture repair
hematoma formation
firbrocartilaginous callus formation
bony callus formation
bone remodelling
heamatoma formation
break rupture blood vessels and a heamatoma forms and phagocytic cells remove dead tissue
firbrocartilaginous callus formation
new blood vessels infiltrate haemotoma as firbroblasts that span the producing a fibrocartilagious callus containing osteoblasts invaded from the periosteum that begin reconstructing the bone
Bony callus formation
the fibrocartilagious callus is converted to cancellous bone called a bony callus by endochondrial and intramembranous ossification
bone remodelling
where cancellous bone is converted to compact bone. (especially in the cortial region)
osteogenesis
mutation in COL1A gene incorrect production of collagen 1 fiber weak bones and increased fracture risk shorten height and stature mainly effects children as don't live past adulthood
rickets
mainly effects children vitamin D deficiency poor calcium mobilidsation ineffective mineralisation weakened bone development soft bone shortened height and stature painful to walk
characteristic bowed legs
osteomalacia
rickets in children
vitamin D deficiency - low mineralisation, increased osteoid
increased calcium reabsorption
e.g protection from sunlight-produces vit D
osteoporpsis
primary type 1 - postmenapausal women due to an increase in osteoclast number loss of oestrogen after the menopause type 2 - occurs in oldre men and women due to the loss of osteoblast function loss of both oestrogen and androgen
secondary
result of drug theapy
processes affect bone remodelling
metabolic bone diseases
osteoporosis risk factors
insufficient calcium intake
exercise
cigarette smoking in women
anchondroplasia
FGF3 mutated gene
effected endochondrial ossification affected
