Bone & cartilage Flashcards
Main roles of bone & cartilage in musculoskeletal system
Support
protection
movement
storage
blood cell production
shock absorption
What are the 3 bone cells and their roles
osteoblasts - synthesise & secrete osteoids
osteocytes - maintain matrix
osteoclasts - bone resorption
What are cartilage cells called & what is their function
Chondrocytes - maintain cartilage matrix
What are the different organisational structures in which collagen fibres are deposited
Woven bone - quick & dirty - young growing animals & fracture repair
Lamellar bone - structurally superior, collagen fibres are parallel
Bone remodeling steps
- bone excavated by osteoclasts (form cutting cone)
- bone replaced by osteoblasts
- form concentric lamellae of lamellar bone on walls surrounding in growing blood vessels
- form secondary osteon
Similarities & differences of bone & cartilage
Similarities:
both provide structural support
can repair themselves to some extent
differences:
structure (bone dense - cartilage soft)
composition (bone = collagen & calcium phosphate - cartilage = collagen & proteoglycans)
blood supply (bone rich - collagen limited)
Types of cartilage
Hyaline/articular:
- joint surfaces & precursor to bone in embryonic skeleton
- inside bone as center of ossification
- mostly type II collagen
White fibrocartilage:
- In areas requiring tough support (e.g. intervertebral disks)
- Lots of collagen
- Type I & II collagen
Elastic:
- e.g. pinna of ear, auditory canal & larynx
- keeps tubes open
contains elastin
How does structure of bone relate to its biomechanical properties
Highly organised & dense tissue – provides strength & stiffness
Network of mineralised collagen fibres (osteons)
Microscopic pores for diffusion of nutrients & waste products
Allow bone to resist deformation & support weight
How does structure of cartilage relate to its biomechanical properties
Softer & more flexible
Matrix contains negatively charged proteoglycans that attract water to create compressible hydrogel
Organised to resist compressive forces – good shock absorber
Viscoelastic properties – allowing it to deform & recover shape
What is a stress fracture?
Syndrome involving localised bone injury associated with fatigue damage subsequent to repetitive loading
Strengths & weakness of bone
Strengths:
- strength & stiffness
- healing capacity
- mineral storage
Weaknesses:
- brittle
- long healing time
Differences between primary & secondary osteons
Formation:
1- during fetal development
2- after primary bone tissue is remodeled
Organisation:
1- poorly organised
2 - highly organised
Size:
1- small (outer later of bone tissue)
2- large (inner layer of bone tissue)
Function:
1- temporary scaffold for growth & development of bone tissue
2- provide strength & stiffness of mature bone tissue
What is Haversian canal
Central channel running through center of osteons
Contains blood vessels, lymphatic vessels & nerves that supply bone tissue with oxygen and nutrients
What are lamellae
Concentric layers of mineralised collagen fibres surrounding Haversian canal
Provide bone tissue with strength & stiffness
What are lacunae
Small spaces between lamellae
House osteocytes
What are canaliculi
Small channels that connect lacunae to each other & Haversian canal
Allow for exchange of nutrients & waste products between osteocytes & blood vessels
What is the cement line
Thin layer of mineralized tissue that separates osteons
What are interstitial lamellae
Irregularly shaped fragments of lamellae located in between osteons
Old osteons that were partially resorbed & remodeled during bone growth
