Bone tissue and structure Flashcards
Why can bone tissue be classified as living
It contains cells
What does ECM stand for
Extracellular matrix
What is bone tissue composed of
Connective tissue and the extracellular matrix
What are the two components of the extracellular matrix
Organic and inorganic
What percentage of the ECM is organic
33%
What makes up the organic ECM
Collagen (protein) and proteoglycans
Purpose of organic ECM
Provides flexibility to resist tension
What percentage of the ECM is inorganic
67%
What makes up the inorganic ECM
Hydroxyapatite and other Ca minerals
Purpose of the inorganic ECM
Makes the bone hard and provides strength
What percentage of bone weight do cells make up
2%
Bone tissue contains what four cells
Osteogenic
Osteoblasts
Osteocytes (mature bone cells)
Osteoclasts
What is the main purpose of the four cells
To maintain bone homeostasis
What do osteogenic cells do
Stem cells that produce osteoblasts
What do osteoblasts cells do
Makers - produce new bone matrix
What do osteocytes cells do
Recycle protein and minerals from matrix (maintainers).
Control if bone needs to be produced or removed
What do osteoclasts cells do
Remove bone matrix (destroyers)
What is the structure of compact bone
Osteon structure
What is the structure of cancellous bone
Trabecular structure
What are the compact units that make up compact bone called
Osteons
What are the 4 components of an osteon
Central canal
Lamallae
Lacunae
Canaliculi
What is the central canal
Cavity in the center of the osteon containing blood vessels and nerves
What is the lamallae
Series of cylinders formed of ECM around the central canal
What is the lacunae
Lakes for osteocytes within the lamallae
What is a canliculi
Channel for osteocytes through ECM
Microscopic view of compact bone
Made up of circumferential lamallae and osteon units
Macroscopic view of compact bone
- Dense and impenetrable
- Foramina for nerves and blood supply
Cancellous bone microscopic structure
Trabeculae (branches of lamella bone)
Where are Osteocytes located in cancellous bone
In lacuna in between lamallae
Why does cancellous bone not contain a central canal
Blood vessels and nerves can get directly to osteocytes in the centre through the canaliculi
Why do cancellous bones have a trabecular structure
- Resists force from multiple directions
- Directs force from body weight in single direction down shaft
- Spreads force distally
What is appositional growth
Growth in the diameter of a bone
How do bones grow and the diameter change
-Osteoblasts add bone matrix in lamallae to the bone surface
- Osteoclasts remove bone from the medullary cavity (center)
What is bone homeostasis
Balance in osteoblast and osteoclast activity
What is bone remodelling
- Possible shape change throughout life to resist strain.
- Possible through bone constantly being formed and destroyed
