bone cells Flashcards
bone forming cells
osteoblasts
origin of osteoprogenitor
UMCS
LM of osteoprogenitor
shape;small and spindle
nucleus;oval
cytoplasm;pale basophilic
EM of osteoprogenitor
few organelles;mainly polysomes
Function of osteoprogenitor
convert to osteoblast during bone formation
origin of osteoblast
from osteoprogenitor cells
site of osteoprogenitor and osteoblast
in cellular layer of perichondrium;lining haversian canals;in endosteum
mention functions of osteoblast
Bone formation by;
1-secretion of osteoid(uncalcified organic component)
2-secretion of alkaline phosphatase enzyme
3-osteoblast+lacuna=osteocyte
function of alkaline phosphatase enzyme
deposition of calcium salts from the blood into bone matrix (bone mineralization)
LM pic of active bone cell
shape;cuboidal or columnar arranged in 1 row
nucleus;eccentric and pale
cytoplasm;deep basophilic with negative gogi image
EM pic of active bone cell
ultrastructura features of protein synthesizing cells
unit bone cells
osteocyte
origin of previous cell
osteoblast entrapped in lacuna
function
maintenance of bone matrix
site
inside lacuna of bone matrix
LM pic
shape;flattened cells with many processes
nucleus;deeply stained
cytoplasm;deeply basophilic
EM pic
what is canaliculi
processes of osteocytes are present within minute places called canaliculi
-lacuna and canaliculi interact with eachother
how do osteocytes get their nutrition
1-small amount of extracellular fluid(in the lacuna and canaliculi surrounding the cells and their processes
2-Gap junction connecting neighboreing osteocytes
can nutrition of osteocytes occur through diffusion
NO
Bone eating cells
osteoclasts
origin
from blood monocytes
function
bone resorption during osteogenesis
site
Resorption bays or howships lacunae
LM pic
shape;irregular outline
size;giant
nucleus;multinucleated(up to 50)
cytoplasm;deeply eosinophilic and vaculated
EM pic
*has 2 surfaces;
1-smooth surface
2-ruffled surface towards the area of bone resorption
*Cytoplasm contains;
1-mitochondria and lysosomes
2-well developed golgi
3-vesicles and vacuoles
mechanism of polarity of osteoclasts
1-smooth border away from area of resorption
2-ruffled border face resorption area
3-mitochondria and lysosomes,vesicles and vacuoles under the ruffled surface
4-nuclei towards the smooth surface
function of polarity
1-Bone resorption(osteogenesis,bone growth and remodeling)
2-digestion of matrix proteins by collagenase enzyme
3-dissolution of hydroxyapatite crystals by acid phosphatase enzyme
