Functions of Bone?
Weight bearing, support, protection and storage of minerals for blood formation.
What are the circular structures in compact bone called?
Central canal of compact bone name?
Horizontal perforating canal of compact bones name?
What is placed around the haversian canal in compact bone?
Osteocytes and concentric rings of bone matrix (lamellaes)
Is spongy bone less or more dense than compact bone?
Does spongy bone have haversion systems? If No what does it have?
No - has a network of lamellated trabeculae filled with bone marrow
What does the orientation of the trabeculae in spongy bone show?
Direction of mechanical force
Two types of bone formation?
Endochondral (long bones) and Intramembranous (flat bones, mandibles, maxilla, clavilcles)
How is endochondral ossification done?
Bone forms as a cartilage model Blood vessels invade the cartilage structure Cartilage replaced with bone, and cartilage kept in epiphyseal growth plate Growth plate eventually ossifies
How is intramembranous ossification done?
No cartilage phase
Mesenchymal cells develop into Osteoprogenitor cells that mature into osteoblasts that start depositing bone
Residual mesenchymal cells develop blood vessels and bone marrow
What 3 cells make up bones?
Osteoblasts Osteoclasts Osteocytes
What does the mineral hydroxyapatite do in bone?
Makes bones stiff and able to support structures and has a high strength under compression
What does collagen do in bone?
Gives bone some flexibility reducing risk of fracture High strength under tension
What do osteoblasts do?
Produce bone matrix, once surrounded by matrix becomes an osteocyte
What do osteocytes do?
Just mature bone, function not well understood
What do osteoclasts do?
Reabsorb bone matrix
What causes osteoporosis?
Re-absoprtion is greater than bone formation
What causes pagents disease?
When re-absorption and formation both are running at high rates
What causes osteopetrosis?
When reabosption is too low
What controls bone mass?
Genes and enviroment
Do mechanical loads regulate bone mass?