1. Bone and Cartilage Flashcards
Macroscopic types of bone (2)
Cortical (compact) - 85% of skeleton
Cancellous (spongy) - §5% of skeleton
Composition of alveolar bone (2)
Cortisol bone
With nutrients canals containing BVs
What makes up ECM of bone
Ground substance
Definition of ground substance
Semi-fluid gel
Composition of ground substance (2)
Polysaccharides
Glycos-amino-glycans (GAGs) - hyaluronic acid, proteoglycans (chondroitin SO4)
Microscopic types of bone (2)
Woven bone
Lamellar bone
Features of woven bone (4)
Rapidly laid down
Irregular collagen deposition
Present in foetus/fracture repair
Contains many osteocytes
Features of lamellar bone (4)
Laid down more slowly
Collagen fibres laid down in parallel
Normal form in adults
Contain fewer osteocytes
Composition of compact bone (5)
Laid down in concentric lamellae Forms longitudinal columns Organised in Haversian systems around central canal Contains lateral canals Canals contain BVs
Composition of cancellous bone (5)
Network of thin trabecular consisting of lamellae
Osteocytes present
No obvious Haversian system
Bone is thin, nutrients can diffuse in
Bone marrow present in space between trabeculae
Where are osteoblasts found and what are they derived from
Surface of bone
Mesenchymal stem cells
Function of osteoblasts
Synthesise and secrete collagen fibres which form a matrix
How is this matrix mineralised
By calcium salts
Definition of osteocyte
Osteoblasts that become trapped within mineralised bone
Where are osteocytes found
Lie within spaces called lacunae
How do osteocytes communicate
Via cytoplasmic processes that lie in canaliculi
Definition of osteoclasts and where do they derive from
Large, multinucleate cells
Derived from haemopoietic stem cells
Function of osteoblasts
Resorb bone
Where are osteoclasts found
Concavities in bone (Howship’s lacunae)
What do osteoclasts control
Bone remodelling (turnover)
What is bone remodelling
Removal and replacement of bone without a change in overall shape
How is bone remodelling regulated (2)
Hormones (PTH, calcitonin)
Paracrines (various cytokines)
What is the reversal line
Histological feature
Scalloped edge shows where bone resorption changes to bone deposition
What does tooth movement require
Remodelling of adjacent soft and hard tissues
When do these movements occur (3)
During eruption
During mesial drift (post-eruption)
Orthodontic forces
Definition of cartilage
Semi-rigid, unmineralised CT that contains a matrix similar to bone
Types of cartilage (3)
Hyaline cartilage
Fibrocartilage
Elastic cartilage
Location of hyaline cartilage (6)
Widespread Larynx Nasal septum Trachea Costal cartilage Articular surfaces Embryonic skeleton (precursor to bone)
Location of fibrocartilage (2)
Intervertebral discs
Pubic symphysis
Location of elastic cartilage (3)
External ear
Epiglottis
Eustacian tube
What what cells are cartilage formed
Chondroblasts
What are chondrocytes and what do they contain
Chondroblasts trapped in the matrix
Stores of lipid and glycogen
Are cartilage cells vascular or avacular
Avascular
Types of bone growth (2)
Endocondral ossification
Intramembranous ossification
Features of endochondral ossification (4)
Long bones
Cartilage precursor
Cartilage proliferation
Cartilage replaced with bone
Features of intramembranous ossification (3)
Flat bones
Bone formed de novo in CT
No cartilage precursor
How does cranial base growth occur
Endochondral ossification
How does sphenoid bone growth occur
Endochondral and intramembranous ossification
Definition of achondroplasia
Genetic defect of cartilage growth
Endochondral bone growth is impaired, intramembranous bone growth is unaffected
How does the condyle grow
Endochondral ossification
