Bone Flashcards
intramembranous ossification
(where bone forms directly within
a vascular connective tissue,
endochondral ossification
bone is preceded by a cartilaginous model
that is eventually replaced by bone
bundle bone
a thin layer of compact, cortical bone lines the tooth socket
which bone gives
attachment to the principal fibres of the periodontal ligament.
bundle bone
lamellar or woven bone has larger and more numerous osteocytes
woven
where is Woven bone seen
sites of fracture repair or in
healing tooth sockets.
It mineralises faster than adult bone so that there
is no lag phase and it is more mineralised. Woven bone is subsequently
replaced by fne-fbred adult lamellar bone.
what % of skeleton is cortical bone
80-85%
bone composition
Bone is a mineralised connective tissue. About 60% of its wet weight is
inorganic material, about 25% organic material and about 15% water.
appearance of inner cortical bone
sieve like, nutrient canals containing blood vessels, penetrated by bundles of sharpeys fibres
ECM of bone
semi fluid gel
long polysaccharide moleucules
GAGs
What fibres in bone
collagen
elastin
what proteins in bone
glycoproteins
- osteocalcin
-osteonectin
-osteopontin
-sialoproteins
proeteoglycans
what are the proteins in bone important for ie function
osteonectin and osteopontin can be use to induce bone repair
woven bone vs lamellar bone in term of speed, arrangement, in who and what type of cells
woven
rapid
irregular
fetus
fracture
many osteocytes
lamellar
slow
parallel collagen fibres
adult
fewer osteocytes
osteoid
unmineralized matrix of bone
what is mineralisation of osteoid dependent on
vitamin D active
is haversian or volkmanns canals horizontal
volkmanns are lateral
haversian are the main ones , longitudinal
how is compact bone formed
laid down in concentric lamellae
can volkmann canals cross the lamellar bone?
yes, they can appear on the external surface of bone
in this case, it appears on the internal surface of the tooth socker (cribriform plate)
where do osteocytes lie
lacunae
canaliculi
cytoplasmic processes of osteocytes for communicating
what is compact bone made of
lamellar bone
what is cancellous bone made of
primarily composed of lamellar bone, but it has a different structural arrangement compared to compact bone.
In trabecular bone, lamellae (layers of bone tissue) are arranged in a lattice-like or trabecular pattern, forming a network of interconnected struts or trabeculae. This network creates spaces between the trabeculae, which are filled with bone marrow and blood vessels.
diff between cancellous and compact bone
Cancellous (Trabecular or Spongy) Bone:
- no haversian systems,
- bone is thinner for diffusion
- epiphysis of long bones, and
- in the interior of other bones.
Compact (Cortical) Bone:
- Haversian
- outer layer (cortex) of all bones
where are osteoblasts located
surface of bones
osteoblasts are derived from what
mesenchymal stem cells
what osteoblasts do
secrete collagen forming an unmineralised matrix which is later mineralised
osteoclasts are derived from what
macrophages
what does osteoclast produce
acid phosphatases that resorb bone
where are osteoclasts located
howships lacunae
what is bone remodelling
removal and replacement of bone tissue without change in overall shape
what cell controls bone remodelling
osteoblasts
produces OPG and RANKL
what regulates bone remodelling
hormones PTH and calcitonin
paracrines
function of PTH and calcitonin
PTH stimulates bone resorption (the breakdown of bone tissue) by activating osteoclasts, cells responsible for breaking down bone.
Calcitonin has an opposing effect to PTH. It inhibits bone resorption by osteoclasts, slowing down the breakdown of bone tissue.
reversal line
change from resorption to deposition
rich in osteopontin and acid phosphatase
where is there alot of bone remodelling in mouth
eruption
post eruptive mesial drift
orthodontic forces
long bone made by what ossification
Long bone mad3 by Endochondral
Flat bone made by Intramembranous
