Bone

Question 1

Bone composition

Answer 1

similar to dentin, HA overlaid on a collagen 1 scaffold

67% inorganic 33% organic (28 collagen and 5 noncollagen)

Question 2

physiological role of bone

Answer 2

structural, calcium homeostasis, reservoir of growth factors,

Question 3

macrostructure of bone

Answer 3

outer dense cortical bone with inner cavity
inner cavity has marrow
highly vascular
circumferential outer ring
concentric lamella- small rings- big outer convering
insterstitioal lammela- former concentric lamellae

Question 4

Osteon

Answer 4

basic function of compact bone
form cylinders parallel to long axis of bone
haversian canal has blood vessel
volkmann canal connects haversian canals

Question 5

cancellous bone

Answer 5

spongy bone
found at ends of long bones, in apposition to joints and associated with marrow spaces
structural support, highly vascularized
blood cell production

Question 6

periosteum

Answer 6

CT layer on outer surface connected by sharpeys fibers

outer fibrous and inner (highly cellular and vascularized)

Question 7

endosteum

Answer 7

loose CT covering in inner surface

seperates marrow from bone

Question 8

osteoblasts

Answer 8

mononucleated cells which synthesize osteoid matrix
mesenchyme origin
differentiate in response to cascade of growth factors
formation and repair
communicate through gap junction
secrete matrix and grwoth factors
after formation flatten and form bone lining cells

Question 9

osteocytes

Answer 9

osteoblasts embedded in matrix
form interconnected lacunar in bone tissue
ccellular processes which interact with surrounding bone tissue
possibly work in conjunction with bone lining cells

Question 10

osteoclasts

Answer 10

large multinucleated- fusion from monocytes
resorption of bone
activated in inflammation
key marker: TRAP
attach to surface mediated by integrin, forms ruffled border
lamina limitans is demineralized bone zone between howships lacunae and intact bone
transcytosis of matrix components

Question 11

control of bone formation

Answer 11

complex itneractions between osteoblasts and clasts
osteoblasts regulate osteoclasts function: RANK-RANKL-OPG
see slides

Question 12

Endochondral Formation

Answer 12

formed from cartilage pattern
collagen broken down by chodoclasts allowing penetration of vasculature, mesenchymal cells differentiate to osteoblasts
bone matrix surrounds remaining minerlaized collagen froming primary spongiosa
osteoclasts gradually remove minerlaized cartilage and devvelop marrow cavity
secondary growth centers from epiphysis of long bones

Question 13

intramembranous formation

Answer 13

mesenchymal cells condense in fibrous CT and differentiate to OB.
osteoid secreted then pentrated by vessels to make woven bone
remodled

Question 14

sutural bone growth

Answer 14

fusion of skull plates, allow for brain to grow

inner cambian layer associated with periosteum and outer capsular layer

Question 15

bone remodling and repair

Answer 15

consistantly being remodled
formed around periosteum while remodeled from marrow cavity (allows growth)
many factors control this
primary osteons replaced with secondary then tertiary ect

Question 16

cone of repair

Answer 16

cutting cone and filling cone <>
osteoblasts make a cement line
gradual replacement allows it to function while repairing