Bones Flashcards
bone tissues are called?
osseous tissues
list down function of bone tissue
protection
support
storage of calcium, phosphate and some other ions
homeostatic regulation of blood calcium level
how many % is organic part of bones
50%
what does organic part of bone comprises of?
collagen and non collagenous proteins
what type of collagen?
type I AND type V
how many percent of organic is collagenous proteins?
90%
non collagenous protein comprises of?
proteoglycans
adhesive glycoproteins
osetocalcin
non-collagenous protein function in bone?
proper growth and repair
function of collagenous?
provide strength, resistance to tensile stress
what are proteoglycans in bone
chondroitin sulfate, keratan sulfate, hyaluronic acid
what are glycoproteins in bone?
osteopontin, osetonectin and sialoproteins I AND II
FUNCTION of glycoprotein?
addhesion of collagen fibers and bone cells to minerallized bone matrix
percentage of in organic matter in bone?
50%
what is the in inorganic matter
mainly hydroxyapatite, calcium, phosphate bicarbonate, magnesium and citrate ions.
the hydroxy crystals are in association with what type of collagen?
type I
4 cells of bone tissue
osteoprogenitor, osteoblast, osteocytes
where osteoprogenitor cells are found?
inner layer of periosteum, and endosteum. lines the haversian canal and volkmann’s canal
what is the stain of osteopro
basophilic
osteopro differentiate to make up?
osteoblast
osteopro are derived from
embryonic mesenchymal cells
osteocytes are?
non dividing bone forming cells
osteocytes secrete what component of the bone ? organic or inorganic
organic component
the unminerallized bone matrix secreted by osteblast are called?
osteoid
what is the staining of osteoblast?
basophilic
shape of active osteoblast?
cuboidal or columnar
what is the main type of protein secreted by osteoblast?
collagen type I
how are osteocytes formed from osteoblast?
when the osteoblast are completely surrounded by the secreted bone matrix they transform into osteocytes
cytoplasmic process on osteoblast do what and release what?
they connect the osteoblast with the osteoid and it releases the enzyme alkaline phosphate
function of alkaline phosphate on bone?
cleaves phosphate ions from other molecules n increases the concentration of phosphate inside
what other cells take part in the formation of calclium phosphate crystals
osteocalcin (increase the level of calcium)
inactive osteoblast in adults are found in?
periosteum and endosteum
what receptor is present in osteoblast? n what does it do?
receptor for parathyroid stimulating hormone. it releases osteoclast stimulating factor
mature osteoblast are called?
osteocytes
osteocytes are present in the place at their specific place called?
lacuna
how osteocytes communicate with neighboring osteocytes
narrow tubular channels called canaliculi
dentrites join what to what in osteocytes
join the canaliculi to a similar process in the neighboring cells
the space b/w plasma membrane and walls of lacunae and canaliculi are called?
periosteocytic space
function of osteocytes
maintenance of bone matrix and blood calcium level
how osteocytes maintain blood calciumLEVEL
osteocytes release enzyme called as metalloproteinases that degrade the bone matrix releasing the calcium ions into the periosteocytic space.
FUNCTION of osetoclast
resorption, remodeling and renewal
where are osteoclast found on surface undergoing resorption
on resorption bays
how does osteoclast stain
acidophilic
osteoclast shape and organelles and structures it contains?
very large, multinucleated, lysosomes, golgi complex and many mitochondria
the periphery of osteoclast contains finger like projections called?
ruffle border
function of ruffle border
it makes contact of the bone surface to the resorption bay
difference b/w microvilli and ruffle border?
ruffle border undergo change of shape and structure because it contracts and retracts
what is the clear zone
the periphery of ruffle border has a ring like structure of cytoplasm that is devoid of all organelles.
what is clear zone rich in
actin filaments
what does actin filaments do
they anchor the cell membrane of sealing zone to the howships lacuna and makes up the subsetoclastic compartment
what does osteoclast secrete into substeoclastic comparment?
hydrogen ions, hydrolytic enzymes, collagenase
what does hydrogen ions do in bone?
make the microenviroment acidic and helps in dissolving bone mineral
what does non lysosomal and lysosomal hydrolytic enzymes do? are their eg
collagenase and gelatinase and they degrade and dissolve the collagen of the decalcified bone
outer covering of bone
periosteum
endosteum covers what part of the bone
inner part of the bone like the medullary cavity or spongy parts of the bone
spongy bone definition
bone substance is in the form of slender spicules or trabeculae with interconnecting cavities
primary bone called
immature bone or woven bone
primary bone has abundant what type of bone cells
osteocytes
where are primary bones found?
embryonic develpment, fetal or bone repair
where pri bone is not replaced by sec bone
alveolar sockets of teeth and where tendons are inserted into bone
secondary bone is called
mature bone or lamellar bone
sec bone composed of
thin layers on bone matrix lamella
haversian system or osteon
the bulk of the compact bone is composed cylindrical subunits called haversian system
haversian canal
lamella are arranged concentrically around a canal called as haversian canal
haversian lamellae
the lamellae constitutes the osteon are called haversian lamellae
cement line
the boundary of the osteons which are mineralized and contains collagen fiber, proteoglycans and glycoproteins
look of haversian canal cross sectional
round openings surrounded by concentric haversian lamella
Haversian canal longitudinal view
slits bordered by column of lamellae
perforating canals or volkmann’s canal
the haversian canal is connected to the marrow, periosteum and to each other by an oblique canal
volkmann canal contains
bloood capillaries
interstitial lamella
lamellae present at irregular intervals between osteons
outercircumfrential lamellae
lamellae present on the outer surface of the bone
inner circumferential lamellae
lamellae beneath the endosteum lining the medullary cavity
process of bone formation
osetogenesis or osification
two types of ossification
intramembranous and endochondral
intramembranous ossification
mesenchymal cells becomes condensed becomes sheet or membranes
membrane become vascularized by ingrowth of capillaries. osteoblast are formed in the vascularized area. osteoblast secrete osteoid
osteoid is deposited in the forms of spicules and trabeculae and have osteoblast on the surface
osteon minerals with calcium phosphate
osteoblast become osteocytes
primary bone and then secondary bone in intramembranous
at the first many bony spicules are formed and arranged as trabeculae and it is spongy in nature, the trabeculae has undifferentiated mesenchymal cells that make up the marrow
the spongy bone is replaced by compact bone and makes up secondary bone
endochondral ossification steps
- formation of miniature cartilage model
- continued growth of miniature model which act as scaffold for bone growth
- replacement and resorption of cartilage and replaced by bone
primary centre appears when in intrauterine life
3 month of intrauterine life
seconary centre appears
after birth
growth of bones in length is done by ?
epiphyseal growth plate
five successive zones of apiphyseal cartilage
resting zone proliferation zone zone of cartilage hypertrophy zone of cartilage calcification zone of ossification
resting zone
zone of reserve cartilage
no active matrix secretion
no cellular proliferation
zone of proliferation
cartilage cells proliferate
divide mitotically
secretion of cartilage matrix actively
zone of hypertrophy
the cartilage cells undergo hypertrophy and increase in size with their lacunae
zone of calcification
the hypertropvhied chondrocytes die
and the matrix is calcified by hydroxyapatite
zone of ossification
osteoprogenitor cells and blood capillaries enter as the diaphyseal side and differentiate into osteoblast on the surface of calcified matrix . osteoblast deposit bone and the cartilage in the core of spicules disappear
growth in diameter
the osteprogenetor cells in the periosteum continously divide and differentiate into osteoblast that deposit a new layer of bone matrix
bone repair after injuriy
the area of blood clotting gets invaded by blood capillaries and osteoprogenitor cells.
granulation tissue is formed
fibroblast produced collagen fibers
periosteal cells make chondroblast that makes up the fibrocartilage callus (hyaline cartilage)
osteoprogenitor cells differentiate into osteoblast and deposit bone in peripheral part and makes the bony callus
first trabeculae of primary bone join the spongy bone fragments
primary spongy bone is later changed into secondary compact bone
types of cell in synovial membrane
type A and type B
type A cells
macrophage like synovial cells
Type B cells
fibroblastic synovial cells
synovium contains
nonsulfated glycosaminaglycans hyaluronan
