Bones Flashcards
What are osteoprogenitor cells
Stem cells that give rise to osteoblasts
What is the function of osteoblasts?
To produce bone
What is the Function of osteoclasts?
Resorption of bone
What is in the extracellular matrix of bone
Calcium hydroxyapatite
What does calcium hydroxyapatite do
Give strength to bones
What are osteoprogenitor cells derived from
Mesenchyme
What secretes osteoid
Osteoblasts
What is osteoid
Unmineralised bone
How are osteocyte connected
Canaliculi which supplies the blood
What are osteoclasts derived from
Monocytes
What histological feature does osteoclast absorption of bone produced
Howship’s Lacunae
What are Howship’s Lacunae?
Depressions in the surface of bone
What are the modes of bone formation
Membranous or endochondrial
What are the origins of bone
Primary (woven)
Secondary (lamellar)
What is Osteoid?
An extracellular matrix rich of type 1 collagen, glycosaminoglycans and proteoglycans 
What do glycosaminoglycans include?
Compounds such as osteocalcin  which has a high affinity for calcium ions
What do parallel sheets of osteoid produce?
Lamellar bone
How is woven bone produced?
Osteoid produced rapidly by osteoblasts
When is woven bone produced?
In fetal life and at fracture site
When does osteoid mineralise
When there is a high local concentration of calcium and phosphate ions
What enzyme aids mineralisation of osteoid?
Alkaline phosphatase
What does osteocalcin do
Binds calcium ions to Osteoid.
What is calcium deposited in bone as?
Calcium hydroxyapatite
What is in secondary bone?
Central Haversian Canal containing blood vessels
Concentric rings of lamellar bone with entrapped osteocytes
Which bones form from intramembranous ossification
Flat bones of the skull
Which bones form from endochondral ossification
All except flat bones of the skull and some cortical bones
Where are secondary centres of ossification
In the head or epiphysis of bones
What are synovial joints lined by
Hyaline cartilage (articulated surface) Synovium (inner surface)
What are type A synovial cells
Phagocytes
What are type B synovial cells
Rich in rough endoplasmic reticulum and secrete synovial fluid
