Line 93: Line 93:  
****Have receptors for [[Bones - normal#Bone resorption|PTH]]: contract in response -> provide space for osteoclasts to attach
 
****Have receptors for [[Bones - normal#Bone resorption|PTH]]: contract in response -> provide space for osteoclasts to attach
 
***When inactive - less cytoplasm -> flattened
 
***When inactive - less cytoplasm -> flattened
   
**'''Osteocytes''': osteoblasts embedded in their own matrix; reside within '''lacunae''' and are interconnected via channels forming '''canaliculi'''
 
**'''Osteocytes''': osteoblasts embedded in their own matrix; reside within '''lacunae''' and are interconnected via channels forming '''canaliculi'''
 
***'''Canaliculi''' create connections to form a huge neural-like junctional organization
 
***'''Canaliculi''' create connections to form a huge neural-like junctional organization
Line 99: Line 98:  
***Reach through canaliculi in mineralised bone matrix
 
***Reach through canaliculi in mineralised bone matrix
 
***Regulate composition of bone fluid
 
***Regulate composition of bone fluid
   
**'''Osteoclasts''': giant (multinucleate monocytes) cells which act to resorb bone ECM
 
**'''Osteoclasts''': giant (multinucleate monocytes) cells which act to resorb bone ECM
 
***Histologically:
 
***Histologically:
Line 112: Line 110:  
****Have receptors for [[Bones - normal#Bone resorption|calcitonin]]
 
****Have receptors for [[Bones - normal#Bone resorption|calcitonin]]
 
****Involute their brush border in response
 
****Involute their brush border in response
   
**Osteoblasts, osteocytes, chondroblasts and chondrocytes are derived from stromal fibroblastic system ('''osteoprogenitor cells'''); osteoclasts from haematopoietic system
 
**Osteoblasts, osteocytes, chondroblasts and chondrocytes are derived from stromal fibroblastic system ('''osteoprogenitor cells'''); osteoclasts from haematopoietic system
  
1,351

edits