Bone biology and fracture repair Flashcards
What could osteoprogenitor cells potentially develop into?
Fibroblasts, chondroblasts, or osteoblasts (-> osteocytes)
What is linked with the amount of mineral deposited into the bone?
Calcium homeostasis so PTH and calcitonin
What growth factors are involved in bone turnover following injury or inflammation?
TGFb bone resorption/ formation
IL-1 bone resorption
TNFa bone resorption
Prostaglandins bone resorption / formation
What are osteoclasts?
Multinucleate cells derived from the bone marrow.
What are osteoclasts responsible for?
Bone removal
Where are osteoclasts?
They lie in Howship’s lacunae on surfaces of bone being resorbed by enzymic digestion, in an extracellular vesicle.
What can impact osteoclast activity?
Calcitonin reduces activity.
Vitamin D increases activity.
PTH acts on osteoblasts which can mediate effects on osteoclasts - increasing their activity
What is bone matrix?
A mixture of osteoid and collagen
What is osteoid?
Composed of glycoprotein and proteoglycan that probably confers its propensity to mineralise.
Organisation of collagen in woven bone?
Haphazardly arranged fibres
Organisation of collagen in lamellar bone?
Fibres are in concentric or parallel bundles.
What do cement lines indicate?
Periods of bone resorption (appear scalloped) or deposition (smooth)
Effects of vitamin C on collagenous and non-collagenous proteins in bone.
Necessary to provide 4-hydroxyproline to stabilise collagen molecules.
Deficiency leads to a failure of collagen production.
Effects of vitamin D on collagenous and non-collagenous proteins in bone.
Both deficiency and excess produce lesions
Effects of vitamin A on collagenous and non-collagenous proteins in bone.
Excess produces degeneration of cartilage.
