MS1: Generalities Flashcards
describe the characteristics of a bone
- highly vascular CT
- most rigid CT
- contains org nd inorg substances
- undergoes constant metabolism and remodeling
what are the shapes of bones
- long
- short
- irregular
- flat
- cuboidal
- sesamoid
describe the structure of flat and cuboidal bones
it has an outer and inner layer of compact bone with cancellous bone in between
constitutes to 80% of the skeleton
compact bone
describe the structure of compact bone
- has tightly packed osteons or haversian systems
what connects osteons
volkmanns canals
what is interstitial lamellae
space between osteons or kung san sila nakapatong
what is cement line
outer border of osteons
it connects interstitial lamellae
fibrils but does cross the cement line
describe the characteristic of compact bones
slow turnover rate
higher modulus - less stretch
more stiff
what are the contents of compact bones
arterioles
venules
cappilaries
nerves
lymphatic channels
describe cancellous bone
high turnover rate
smaller modulus - more stretch
more elastic
describe the remodeling in cancellous bones
happens according to lines of stress
what are the layers of long bone from superficial to deep
periosteum - outer fibrous cover
cortex - compact bone w haversian systems
endosteum - spongy bone layer
medullary canal
what is the physis
separates epiphysis from metaphysis
epiphysial plate in children
found at the ends of long bones from distal to proximal
epiphysis
physis
metaphysis
diaphesis
compare lamellar vs woven architecture
lamellar - more organized or alternating layers
- normal architecture of cortical nd cancellous
woven - interconnected nd has no pattern
- immature or pathological
- woven matures to lamellar
where are bone cells from
mesenchymal stem cells
compare membranous vs cartilaginous bone formation
membranous: stem cell - osteoblast - bone
cartilaginous: stem cell - chondrocyte - bone
give examples of membranous bone formation
skull, facial bones, clavicle
give examples of enchondral bone formation
majority of bones
how early does enchondral bone formation start
6 wks in womb - at birth some ossified some not
ossifies until 20 yrs old
describe osteoblasts
BUILDS
forms bone from organic non-mineralized matrix
from mesenchymal stem cells affected by interluekins, PDGF, IDGF - becomes kung ano man
describe osteocytes
LIVING CELLS
90% of cells in mature skeleton
former osteoblast
regulates extracellular calcium nd phosphorus in bones
describe osteoclasts
CONSUMES - ruffled brush border
multinucleated
from hematopoietic blood cells - macrophages
where does bine resorption occur
howship’s lacunae
what are osteoprogenitor cells
from mesenchymal cells
lines haversian canals, endosteum, periosteum
compare the differentations of osteoprogenitor cells
osteoblast - low strain, high O2 tension
cartilage - intermediate strain, low O2 tension
fibrous tissue - high strain
comprises 40% of dry weight of bone
organic components
comprises 60% of dry weight of bone
inorganic componenets
what makes most of organic components in bones
collagen - 90%
what are the organic components of bones
collagen - type 1 for tensile strength or elasticity
proteoglycans - compressive strength
matrix proteins - mineralizations and bone formation
growth factors and cytokines
what are the inorganic compounds of bones
calcium hydroxyapatite - hard component for compressive strength
calcium phosphate
what is wolffs law
remodeling occurs to mechanical stress
what is heuter-volmann law
compressive forces inhibits growth - tension promotes growth
compare cortical vs cancellous bone remodeling
cortical - osteoclastic tunneling
- osteoclasts cuts cone tunnels
- osteoblast layer on tunnels
- deposition of lamellae
cancellous - osteoclasts resorp bones then osteoblasts lay new bone
how much cardiac output does the bone receive
5-10%
what are the 3 systems long bones receive blood
nutrient artery - from systemic arteries
- enters diaphyseal cortex via nutrient forame
- enter medullary canal to ascend/descend arteries
metaphyseal-epiphyseal - from periarticular vascular plexus - genicular arteries
periosteal - capillaries in outer third of mature diaphyseal cortex
describe the arterial blood flow in bones
centrifugal - inside to outside
- high psi nutrient artery to low psi periosteal system
describe blood flow in fractures/immature/developing
centripetal - outside to inside
- nutrient artery system is disrupted
- get blood from outside
describe venous blood flow in bones
centripetal - outside to inside
- cortical capillaries to venous sinusoids
- drains to emissary venous system
what is the periosteum
ct membrane that coves bone
highly developed in children
compare the layers of periosteum from superficial to deep
fibrous - less cellular contiguous w joint capsule
cambium - loose nd vascular
- has cells that can become osteoblasts that enlarges diameter of bone during growth or form periosteal callus during fracture healing
bone marrow is the source of what cells
progenitor cells
compare red and yellow marrow
red marrow - hematopoetic - produces
- 40% water, 40% fat, 20% protein
- changes to yellow marrow w age
yellow marrow - inactive
- 15% water, 80% fat, 5% protein
what is physis
growth plates in immature bones
what are the physeal cartilage zones
reserve
proliferative
hypertrophic
what is the reserve zone
- cells store lipids, glycogen and proteoglycans
- decreased O2 tension
what is the proliferative zone
- longitudinal growth - stacking chondrocytes
- inc O2 = inc proteoglycans = inhibit calcification
- cellular proliferation and matrix production
what disease affects the reserve zone
gauchers - lysosomal storage disease
what disease affects proliferative zone
gh - gigantism/achondroplasia
what is the 3 zones of hypertrophic zone
maturation - chondrocytes enlarge and hypertophy
degenerative zone - chondrocytes increase 5x more and matrix prepared for calcification
provisional calcification - chondrocytes degenerate and die = calcium is released = matrix will calcify
what is the hypertrophic zone
osteoblasts migrate from sinusoidal vessels and uses cartilage to form bone/calcify
low oxygen tension and dec proteoglycan aggregates
what diseases affect hypertrophic zone
maturation nd degenerative - mucopolysaccharide disease
provisional calcification - rickets
