Bone: Introduction, Acquired Disorders, Joints,

Question 1

Bone matrix is? And its components are?

Answer 1

Extra cellular component of bone.

It is

• 65% mineral: hydroxyapatite
• 35% organic osteoid: type 1 collagen, GAGs, other proteins

Question 2

Major protein of bone matrix

Answer 2

Type 1 collagen

Question 3

A protein unique to bone?
Its function?
Its clinical significance?

Answer 3

Osteopontin / osteocalcin

Function: role in bone formation, mineralisation, calcium homeostasis.

C/S: Produced by osteoblasts. Hence, serves as sensitive and specific marker for osteoblast activity.

Question 4

Histologic types of bones and their differences

Answer 4

Woven and lamellar

Woven

• rapidly produced
• disorganised arrangement of TYPE I COLLAGEN
• hence, less structural integrity
• eg. Foetal development and fracture repair

Question 5

Presence of which bone is always pathological in adult?

Answer 5

Woven bone

Question 6

Osteoblast derived proteins

Answer 6

1. Type I collagen
2. Calcium binding proteins
   
   • osteoNECTIN
   • bone sialoprotein
3. Cell adhesion protein
   
   • osteopontin/osteocalcin
   • fibronectin
   • thrombospondin
4. Cytokines
   
   • IL1
   • IL6
   • RANKL
5. Enzymes: collagenase, ALP
6. GFs: IGF-1, TGFb, PDGF
7. Mineralising proteins: osteocalcin/osteopontin

Question 7

Anlagen

Answer 7

• Cartilage mold, on which bone develops

- Synthesised by mesenchymal precursor cells