Bone & cartilage

Question 1

Main roles of bone & cartilage in musculoskeletal system

Answer 1

Support
protection
movement
storage
blood cell production
shock absorption

Question 2

What are the 3 bone cells and their roles

Answer 2

osteoblasts - synthesise & secrete osteoids
osteocytes - maintain matrix
osteoclasts - bone resorption

Question 3

What are cartilage cells called & what is their function

Answer 3

Chondrocytes - maintain cartilage matrix

Question 4

What are the different organisational structures in which collagen fibres are deposited

Answer 4

Woven bone - quick & dirty - young growing animals & fracture repair
Lamellar bone - structurally superior, collagen fibres are parallel

Question 5

Bone remodeling steps

Answer 5

1. bone excavated by osteoclasts (form cutting cone)
2. bone replaced by osteoblasts
3. form concentric lamellae of lamellar bone on walls surrounding in growing blood vessels
4. form secondary osteon

Question 6

Similarities & differences of bone & cartilage

Answer 6

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)

Question 7

Types of cartilage

Answer 7

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

Question 8

How does structure of bone relate to its biomechanical properties

Answer 8

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

Question 9

How does structure of cartilage relate to its biomechanical properties

Answer 9

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

Question 10

What is a stress fracture?

Answer 10

Syndrome involving localised bone injury associated with fatigue damage subsequent to repetitive loading

Question 11

Strengths & weakness of bone

Answer 11

Strengths:
- strength & stiffness
- healing capacity
- mineral storage

Weaknesses:
- brittle
- long healing time

Question 12

Differences between primary & secondary osteons

Answer 12

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

Question 13

What is Haversian canal

Answer 13

Central channel running through center of osteons

Contains blood vessels, lymphatic vessels & nerves that supply bone tissue with oxygen and nutrients

Question 14

What are lamellae

Answer 14

Concentric layers of mineralised collagen fibres surrounding Haversian canal

Provide bone tissue with strength & stiffness

Question 15

What are lacunae

Answer 15

Small spaces between lamellae

House osteocytes

Question 16

What are canaliculi

Answer 16

Small channels that connect lacunae to each other & Haversian canal

Allow for exchange of nutrients & waste products between osteocytes & blood vessels

Question 17

What is the cement line

Answer 17

Thin layer of mineralized tissue that separates osteons

Question 18

What are interstitial lamellae

Answer 18

Irregularly shaped fragments of lamellae located in between osteons

Old osteons that were partially resorbed & remodeled during bone growth