bone Flashcards
The most dynamic structure in the body; greatly affected by nutritional and metabolic changes.
bone
A reservoir for calcium and phosphorus that undergo a constant flux in and out of the bone matrix.
bone
how does the bone respond to injury
by rapid healing
undergoes internal remodeling throughout life without changing its gross apeparance
bone
Bone cells are in contact with each other through cellular processes embedded in tiny channels in the hard bone matrix called
canaliculi
form a system of channels that provide a route by which processes from one osteocyte can contact those of adjacent ones and allow osteocytes to communicate with one another for passage of information, nutrients, and/or wastes from cells near blood vessels to the ones trapped in lacunae.
canaliculi
highly vascular and grows only by appositional method
bone
why do bones cannot grow interstitially
because of its rigidity due to mineralization
functions of bones
forms the skeleton of the body
provides attachment sites for muscles and constitutes the structural framework of the thoracic and abdominal cavities
it houses haemopoietic tissue and serves as reservoir for various minerals
bone
2 division of functions of bones
support and metabolism
the connective tissue sheath of bone which influences the function of bone
periosteum
the 2 components of the periosteum a
outer fibrous layer and inner osteogenic layer
composed of regular DWFCT (collagen fibers) and fibroblast
outer fibrous layer of periosteum
composed of stellate or spindle shaped osteogenic cells from the fibroblast cell line.
inner osteogenic layer of periosteim
surrounds the bone, except at articular surfaces and at many sites of muscle attachment
periosteum
the contents of the periosteum for maintenance of the underlying bone
sensory nerve fibers and a dense network of blood and lymphatic vessels
capable of rapidly producing new bone tissue,
the pluripotent osteogenic layer of periosteum
Bone cavities and canals are lined by
endosteum
this is much thinner than periosteum and outer fibrous layer is loose connective tissue rwathher than dwct
endosteum
responsible for internal remodelling of bone
endosteum
bone is derived from the
mesencgymal connective tissue
bone is consist of
bone cells and bone matrix
principal component of bone
intercellular substance
it gives bone the ability to to ressist snapping and breaking
collagen fibers
(20-30% of total organic material of bone
collagen fibers a
proteoglycans attached with GAGs
amorphous gel like matrix
the unmineralized matrix of the bone.
osteoid
form the osteoid
amorphous substance and collagen fibers
gives bones its
hardness and rigidity
mineralized osteoid
mineralization of osteoid is chiefly from
calcium phosphate and hydroxyl ions
type of bones has 65% mineral content and 35% amorphous substance and
collagen.
mature
matrix component which is a gelatinous mucopolysaccharide that binds the proteoglycans together into large aggregates.
hyaluronic acid
what type of collagen predominates in the matrix of the bone
type 1
what type of collagen is present in the bone
2,3,5,10
form the mineral component of bone
Inorganic salts which range from calcium and phosphate ions to more complex hydroxyapatite
located
in the holes and pores of the matrix collagen fibers
calcium salts
Due to ______, the matrix of bone is poorly
permeable to most nutrients which must subsequently reach bone cells by flowing through the lacunar-canalicular system.
calcification
boen cell components
osteoprogenitor cells, osteoblasts, bone-lining cells,
osteocytes and osteoclasts.
Except for _____, cells found in bone represent different functional
phases of the same cell type
osteoclast
Osteoprogenitor cells differentiate into
osteoblasts
these are bone forming cells
osteoblast
synthesise the organic components of the bone matrix.
osteoblasts
when do osteoblast become osteocytes
after mineralization of the matrix
e responsible for bone resorption.
osteoclast
where do osteoprogenitor cells develop form
mesenchymal stem cells
, these are
flattened cells with pale cytoplasm and an ovoid to oblong nucleus
osteoprogenitor cells
osteoprogenitor cells are found predominantly in the
osteogenic layer of the periosteum and along vessels of the bone marrow
what component of bone does not undrgo mitosis
osteoblast
different ways in which the osteoblast participate in the bone formation
synthesis of type I collagen fibers, non-collagenous proteins,
production of glycosaminoglycans/proteoglycans,
participation in mineralisation of bone matrix and
modulation of osteoclast function.
the youngest and only bone cell capable of mitosis
osteogenic cells
type of bone cells that is spindle or stellate shaped with round or oval nuclei
osteogenic
secretes osteoid at the periphery of the bone trabecula and later, hydroxypatite to harden the osteoid
osteoblasts
osteoblast that is spindle shaped with basophilic cytoplasm dueo to extensive RER and round or oval nuclei
inactive
osteoblast that is cuboidal and polarized so that their round and oval nuclei are displaced to the cytoplasm away from the bone they are working on
active
osteoblasts are located in the
periphery of bone trabeculae or bone spindles
when the matrix is mineralized, the osteoblasts trapped in the matrix differentiates into osteocytes to enter ____
maintenance mode
these bone cells are the same cells in 2 separate physiologic state
osteoblast and osteoclast
bone cells that have stopped secreting the bone matrix or have significantly reduced secretory function
osteocyte
these cells are derived from the osteoblasts that have been trapped in lacunae durimg mineralization
osteocytes
round or oval cells with round or oval nuclei and cytoplasmic processes
osteocyte
may fused to form osteoclast
osteocyet
capable of removing bone matrix through osteolysis
osteocyte
maintains the integrity of bone by supplying nutrients from blood vessels
osteocyte
these bone cells are derive dfrom the same line as the monocytes
osteoclast
large multinucleated cells fromed by the fusion of monocyte precursors
osteoclats
what is the reason for the brush border on the side of the adjacent to thebone surface in osteoclast
to increase surface area for resorption
its foamy acidophilic cytoplasm is due to the
abundant lysosomes and mitochondria
its nuclei are displaced towards the cell border away from the bone edge
osteoclast
osteoclast is located on the
concavities on the bone surface calles resorption lacunae (howship’s)
osteoclast resorb bone by
releasing lysosomal contents n bone surface to digest collagen fibers and hydrogen ions to dissolved mineralized matrix
osteoclasts may be mistaken for
megakaryotes
Histologically, bone tissue can be divided into two types
woven bone and lamellar bon
type of bone accdg to density
cancellous or spongy and compact bone
type of bone accdg to manner of evelopmemt
intramembranous and endochondral ossification
forms the cylinder surrounding the hematopoietic cavity of long bones
compact bone
Develops from cancellous bone by additional deposition of bone substance into existing trabeculae to
form layers called lamellae
compact bone
a network of anastomosing, angular bone trabeculae separated by interosseous spaces
cancellous or spongy bone
spaces between bone trabeculae lined by endosteum and filled with myeloid tissue
interosseous space
an islet of bone atrix
bone trabecula or bone spicule
have osteocytes within lacunae
trabecula
do osteons form
no
since trabecula are quite thin, the osteocytes are nourished by
diffusion from bone marrow via the canaliculi
found in diaphysis of young tubular bone and in flat bones of mature skull
cancellous or spongy bone
this may be developed further into compact bone
cancellous bone
how do compact bone develops from cancellous bone
by additional deposition of bone substance into existing trabeculae to form layers called lamellae
compact bone presents the ff: lamellae
concentric, interstitial, outer circumferential, inner circumferential
compact bone is made up of
osteon
the basic structural unit of compact bone
osteon
these are circular layers of bone substance that surrounds the osteonal canal and constitute the osteon
concentric lamellae
irregular lamellae of bone that filll the spaces between osteons
interstitial lamellae
remnants of old osteons varying in size and shape depending on how old they are and how many new osteons have been organized around them
interstitial lamellae
what makes it possible to a ge a bone
the proportion of osteons to interstital system is predictable with increasing age
circular layers of bone substance that encircle the outer perimeter of bone beneath the periosteum
outer circumferential lamellae
circular layers of bone substance that form the wall of the marrow cavity
inner circumferential lamellae
a cylinder composed of 4-20 concentric lamellae arranged around a central opening
osteont
the central opening in the osteon
osteonal (haversian) canal
the formation of bone directly from or within fibrous connective tissue membranes
intramembranous ossification
the formation of bone from hyaline cartilage models
endochodrial ossification
2 ways of repairing fractued bone
primary and secondary intention healing
type of healing bone without formation of external callus
primary
healing of bone with formation of external callus during therepair process
secondary
stages of bone healing
impact
induction
inflammatory
reparative
remodeling
manifested by bone injury or trauma
impact stage
characterized by torn blood vessels, hemorrhage followed by clot formation and death of bone
impact stage
proliferation of osteogenic cells in the inner layer of the periosteum to form a cellular collar near each bone fragment in the area of the fracture
induction stage
presence ofr redness, pain, swelling and heat in the area of fracture
inflammatory
removal of damage or dead bone tissue and blood clot by inflammatory cells that have migrated to the site of fracture
inflammatory
bonding of the newly formed bone to the dead and live bone
remodeling stage
replacement of hyaline cartilage by bone and eventual return to normal of the fracture portion of the
remodeling stage
migration of collars of osteogenic cells and capillaries from the periosteum and endosteum to the fracture
reparative stage