Structure of Bone and Cartilage Flashcards
What are the two types of bone tissue?
- compact
- cancellous (spongy)
Describe compact bone tissue
homogenous (solid)
- similar to other parts
Describe cancellous bone tissue
network of bone
- small needle-like pieces of bone
- many open spaces
Define osteons
Basic functional units of mature compact bone
Structure of osteons
Osteocytes arranged in
- concentric layers
- around a central canal
- which contains blood vessels
Define lamellae
network of thin plates (similar to osteons)
- structure of cancellous bone tissue
Structure of lamellae
Meshwork of supporting bundles of fibers
- called trabeculae
Composition of bone matrix
- hydroxyapatite
- calcium salts
- collagen fibers
- cells
Proportion of hydroxyapatite in bones
2/3 of bone weight
Proportion of collagen fibers in bones
1/3 of bone weight
What are the bone cells?
- osteogenic cells
- osteoblasts
- osteocytes
- osteoclasts
Osteogenic cells
Produce osteoblasts
Structure:
- periosteum - outer surface of bone
- endosteum - inner surface of bones
osteoblasts
Bone forming cells
Osteocytes
Mature bone cells
- 90-95%
- deep within the bone matrix
Osteoclasts
Bone-destroying cells (5%)
- remove old bone
- dissolve minerals
What cells are involved in bone remodelling?
- osteoblasts (forming)
- osteoclasts (destroying)
Cartilage
Type of connective tissue
- important for bone formation
- strong, flexible & fibrous
Structure of cartilage
- matrix
- chondrocytes cells
- perichondrium (covering)
Matrix (in cartilage)
Firm gel
- contains polysaccharide derivative, chondroitin sulfates
Chondrocytes
Occupy small chambers known as lacunae
Perichondrium
Two layers:
outer fibrous region – protection & attachment
inner cellular layer – growth
What are the types of fibres in cartilage?
- hyaline
- elastic
- fibrocartilage
Describe hyaline
Closely packed collagen fibres
Where is hyaline found?
Between
- ribs-sternum
- joint cavities
- windpipe
Describe elastic
- numerous elastic fibres
- resilient & flexible
Where is elastic found?
- vertebral column ligaments
- ear
Describe fibrocartilage
- densely interwoven collagen fibres
- restricts movement
Where is fibrocartilage found?
Intervertebral discs
What are the two growth mechanisms in cartilage?
- interstitial growth
- appositional growth
What is interstitial growth?
- cell division
- enlarges from within
What is appositional growth?
cells of inner layer of perichondrium undergo repeated cycles of division
- so new layers of cartilage are added to the surface
How does appositional growth work? (2)
- undergo repeated cycles of division
- new layers of cartilage added to surface
