Bone Flashcards
What are the functions of bone?
Weight bearing/support
Protection
Mineral store
Blood formation
What is the gross anatomy of bone?
- Compact bone
- Spongy (trabecular) bone
- Blood vessels
- Medullary cavity
- Bone marrow
- Membranes (periosteum/endosteum)
What is compact bone organised into?
Circular structures known as osteons surrounding a central Haversian canal
What canals run horizontal in bone?
Volkmann’s canals
What is found around a Haversian canal?
Osteocytes and concentric ring of bone matrix known as lamellae
What are other names for spongy bone?
- Cancellous
- Trabecular bone
- Diploe
What is spongy bone?
A network of lamellated trabeculae filled with bone marrow
What does the orientation of trabeculae reflect?
The main directions of mechanical forces
What are the 6 types of bone?
Flat bone Sutural Bone Long Bone Sesamoid Irregular Bone Short Bone
What are the 2 types of bone development?
- Endochondral
- Intramembranous
What is the primary ossification centre?
Where bone formation begins
Where does intramembranous ossification also occur?
Adult cortical bone
What makes up bone?
- Cells (osteoblasts, osteoclasts, osteocytes)
- Extracellular matrix (hydroxyapatite crystals, Type 1 collagen, water)
What do minerals such as hydroxyapatite do in bone?
Make bone stiff and able to support structures as they have high strength under compression
What does collagen do in bone?
Gives bone some flexibility and reduces risk of fracture as it has high strength under tension
What makes bone healthy?
Having a constant balance between bone removal and bone formation
What are osteoblasts?
Immature bone cells created from ostopregenitor cells in the periosteum and endosteum
What is the function of osteoblasts?
To produce bone matrix and initiate calcification
What happens to osteoblasts once they are surrounded by matrix?
They become osteocytes
What are osteocytes?
Mature bone found inside lacunae
What do canaliculi do?
Connect lacunae to each other to allow communication between cells
What are osteoclasts?
- Multinucleate cells derived from monocytes/macrophages
- They are large cells with rough borders
Where are osteoclasts found?
On the bone surface
What is the function of osteoclasts?
To resorb bone matrix
What are Howship’s lacunae?
Resorption pits
What is the extracellular matrix?
It is mainly minerals, protein and water
What kind of collagen is found in the extracellular matrix?
Modified type 1
How is the collagen in the extracellular matrix arranged?
Strongly cross-linked and large gaps within fibres
What do the gaps in the collagen fibres do?
Provide space of hydroxyapatite crystals
What is the orientation of collagen fibres linked to?
Mechanical forces
Name 3 disorders of bone remodelling.
Osteoporosis
Paget’s Disease
Osteopetrosis
What happens in osteoporosis?
Resorption>Formation
What happens in Paget’s Disease?
Increased Resorption/ Formation
What happens in osteopetrosis?
Decreased resoprtion
What is bone mass controlled by?
Genes and the environment
What can cause significant bone loss?
Weightlessness or bed rest
What is particularly effective in maintaining bone mass density?
Resistance and high impact sports
