bone histology Flashcards
confers STIFFNESS (high:stiff:cortical, low:elastic:cancellous)
Young’s modulus of elasticity
COMPACT bone; 80% of skeleton
CORTICAL bone
law of remodeling according to LINES OF STRESS?
Wolff’s law
is transcription factor for: mesenchymal cells - osteoblast
RUNX2
maintains bone; 90% of mature skeleton
osteocytes
antiseptics toxic to osteoblasts?
hydrogen peroxide, betadine, bacitracin
action of PTH?
stimulate OSTEOCLAST activity
lineage of OSTEOCLAST?
MACROPHAGE
action of BISPHOSPHONATES?
INHIBIT osteoclast - ANABOLIC effect
NITROGEN-CONTAINING bisphosphonate?
1000-fold ANABOLIC potency (zoledronic acid, alendronate)
IN BONE DEV’T: osteoprogenitor cells - LOW strain, HIGH O2 tension
osteoblasts/WOVEN bone
IN BONE DEV’T: osteoprogenitor cells - INTERMEDIATE strain, LOW O2 tension
CARTILAGE
IN BONE DEV’T: osteoprogenitor cells - HIGH strain
fibrous tissue
bone collagen type?
type I
ORGANIC component % of bone dry weight?
40%
collagen % of organic component?
90%
decreases solubility, increases strength of collagen?
cross-linking
most abundant NON-COLLAGENOUS bone protein?
OSTEOCALCIN
INORGANIC component % of bone dry weight?
60%
primary composition of bone INORGANIC component?
calcium hydroxyapatite
bone TENSION stimulates?
RESORPTION (osteoclasts)
bone COMPRESSION stimulates?
FORMATION (osteoblasts)
law of BONE GROWTH (compressing inhibits, tension stimulates)
Hueter-Volkmann law
% cardiac output received by bone?
5-10%
bones with LOW blood supply?
scaphoid, talus, femoral head, odontoid
bone’s 3 sources of blood?
NUTRIENT artery, METAPHYSEAL-EPIPHYSEAL system, PERIOSTEAL system
arterial flow in MATURE bone?
centrifugal
arterial flow in FRACTURED/ IMMATURE bone?
centripetal
MAJOR determinant of bone healing?
blood flow
effect of nail REAMING?
devascularization
effect of LOOSE-FITTING nails?
spares cortical perfusion
enlarges diameter of bone in growth and forms periosteal callus?
CAMBIUM (inner periosteum)
composition of RED marrow?
water 40%
fat 40%
protein 20%
composition of YELLOW marrow?
water 15%
fat 80%
protein 5%
types of bone formation?
enchondral, intramembranous, appositional
ENCHONDRAL bone formation?
BONE REPLACES CARTILAGE (e.g. embryonic/ longitudinal growth, fracture callus)
what are the 2 growth plates?
PHYSIS (horizontal),
EPIPHYSIS (spherical)
physeal cartilage zones: RESERVE zone
lipid, glycogen, proteoglycan storage
physeal cartilage zones: PROLIFERATIVE zone
longitudinal growth
physeal cartilage zones: HYPERTROPHIC zone
maturation, degeneration, calcification (rickets, MPS)
INTRAMEMBRANOUS bone formation?
WITHOUT CARTILAGE (e.g. flat bones, distraction osteogenesis, young amputations)
APPOSITIONAL bone formation?
bone enlargement (width), remodeling