locomotor Flashcards
1
Q
bone
A
A mineralized collagen-rich matrix which is very rigid and strong while still retaining some degree of flexibility
2
Q
bone functions
A
• Resistance to compression : inorganic content • Resistance to tension : organic matrix
- Houses bone marrow
- Calcium homeostasis
- Protects vital organs
3
Q
bone cells
A
– Osteoblasts bone forming – Osteocytes a mature osteoblast surrounded by bone matrix – Bone lining cells – Osteoclasts resorption and degradation of existing bone -osteoprognitor cells osteoblast precursors
4
Q
bone structure and function
A
• Bone matrix / mineralisation • Bone remodelling • Bone development – Intramembranous – Endochondral
5
Q
long bone anatomy
A
epiphysis metaphysis diaphysis metaphysis epiphysis
6
Q
epiphyseal growth plate
A
- Specialised zone of cartilage
- Lies between epiphysis and metaphysis
- Site of longitudinal growth
- ‘Closes’ at /after puberty
- Long bone growth stops
7
Q
bone - composition
A
• Cortical (70%) – compact • Trabecular (30%) – cancellous – medullary – spongy bone
8
Q
bone - macroscopic organisation
A
• Proportion of cortical / cancellous bone varies in different parts and types of the bone • Mid bone / diaphysis – most cortical little cancellous bone • End of bone / epiphysis – predominantly cancellous bone
9
Q
compact/ cortical bone
A
• Provides most structural support • Resists bending and torsion stresses – Thicker in mid part of bone
10
Q
microscopic structure of cortical bone
A
• Osteons / Haversian canals – Main structural unit of cortical bone – Bone cylinders 2-3mm long – 8-15 concentric lamellae 0.2mm wide – Axis parallel to long axis of bone – Central cavity with blood vessels and nerve • Volkmann’s canals – Carry blood vessels from periosteum to Haversian system
11
Q
microscopic structure of cancellous/ trabecular/ spongy bone
A
• Found inside cortices • Forms interconnecting network of plates / trabeculae • Provides large surface area for metabolic functions
12
Q
Cancellous / Trabecular Bone
A
• Provides strength without disadvantage of weight • Organisation of trabecular plates is purposeful • Arranged along lines of maximum mechanical stress – Allows transmission of loads – Support areas of maximum stress • More metabolically active than cortical bone – Larger surface area
13
Q
osteoid
A
• Unmineralised bone matrix – produced by osteoblasts • Type I collagen ( 90%) • Non collagenous proteins – Osteocalcin • Marker of bone formation – Osteonectin – Osteopontin – Growth factors
14
Q
bone matrix - microscopic organisation
A
• Lamellar bone – Type I collagen fibres laid down in parallel sheets / lamellae – structurally very strong • Woven bone – collagen fibres randomly arranged – Mechanically weak – Formed when bone is being produced rapidly e.g. foetus or fracture
15
Q
whats needed to from osteoblast
A
transcription factors Runx2 and osterix
