Cartilage, Bone

Question 1

What is Articular Cartilage?

Answer 1

Articular Cartilage is a specialised form of connective tissue that covers and protects the ends of the bones in synovial joints.

Question 2

What are the predominant cartilages in Articular Hyaline Cartilage?

Answer 2

Types II, IX and XI

Question 3

What cell type secretes Type II collage in cartilage formation?

Answer 3

Chondrocytes

Question 4

What are FACIT (Fibril-Associated Collagen with Interrupted Triple Helix) Collagens?

Answer 4

Type II (94%) - Provides tensile strength
Type VI (1%) - Forms fine fibrils in lacunae around cells
Type IX (2%) - On outside of the fibrils, resists shear
Type XI (3%) - Inside of Type II fibrils

Question 5

What is the main function of Proteoglycans?

Answer 5

To trap water contributing to the shock-absorbing capacity.

Question 6

4 main functions of Bone

Answer 6

Provide mechanical support
Permit locomotion
Provide protection
Act as a metabolic reservoir of mineral salts

Question 7

What is bone composed of?

Answer 7

Support cells - Osteoblasts and osteocytes
Osteoid - non-mineral matrix of collagen and glycosaminoglycans
Remodelling cells - Osteoclasts

Question 8

What is Osteoid?

Answer 8

Collagenous support tissue of Type 1 Collagen embedded in a Glycosaminoglycan gel containing specific glycoproteins (Osteocalcin)

Question 9

What cells are involved in synthesis of Osteoid?

Answer 9

Osteoblasts synthise Osteoid and Osteoclasts can erode bone.

Question 10

What are Haversian systems?

Answer 10

Series of irregularly spaced overlapping cylindrical units in the make up of cortical bone.
Each system consists of a central Haversian canal surrounded by concentric lamellae of bony tissue.
Also called an Osteon

Question 11

What are Volkmann’s Canals?

Answer 11

Volkmann’s canals are perforating canals linking central Haversian canals. They carry blood vessels.

Question 12

What are some growth factors produced by the Osteoblasts?

Answer 12

Insulin-like growth factors (IGF)
Platelet-derived growth factors (PDGF)
Basic Fibroblast Growth Factor (bFBF)
Transforming Growth Factor beta (TGF-B)
Bone Morphogenetic Proteins (BMP)

Question 13

What is the role of RANKL

Answer 13

RANKL (Receptor Activator of NF-kappa B ligand interacts with a receptor on Osteoclast precursors called RANK.
The RANKL/RANK interaction results in activation, differentiation and fusion of hematopoietic cells of the osteoclast linage so that they begin the process of resorption.
It also prolongs Osteoclast survival by suppressing apoptosis.

Question 14

What is Osteoprotegerin (OPG)

Answer 14

OPG acts as a decoy receptor agonist for RANKL and it is mainly produced by cells of the Osteoblast linage.
It regulates bone resorption by inhibiting the final differentiation and activation of Osteoclasts and by inducing their apoptosis.