Bone- Cartillage

Question 1

Where do we find cartillage in embryo ?

Answer 1

More prevalent than in adult
Skeleton initially mostly cartilage
Bone replaces cartilage during fetal development & childhood

Question 2

Where do we find cartillage in adult?

Answer 2

Skeleton (e.g. costal cartilage)
Nose
External ear
Trachea & larynx

Question 3

What is cartillage?

Answer 3

Semi-rigid, flexible connective tissue
Support in tissues & organs & scaffold for bone development
Avascular & aneural, obtains nutrition by long range diffusion from blood vessels on its periphery
High mechanical strength

Question 4

What makes up cartillage?

Answer 4

Cells
Chondroblasts (immature and smaller cartillage cells)
Chondrocytes

Extracellular matrix
~75% Water
Mixture of molecules (important for mechanics)
Fibres

Question 5

What are the three types of cartillage?

Answer 5

Hyaline (most common type incl. articular cartilage)
Elastic (e.g. in the external ear)
Fibrocartilage (e.g. intervertebral discs)

Question 6

Characteristics of hyaline cartilage?

Answer 6

Found in articular, costal & nasal c., also in larynx, trachea, bronchi & epiphyseal growth plates
Chem. composition of matrix different between these
Glassy appearance
Weakest type of cartilage

Question 7

Characteristics of elastic cartillage?

Answer 7

Found in external ear, larynx & epiglottis (helps to maintain their shape)
Flexible & resilient
Contains elastic as well as collagen fibres

Question 8

Characteristics of fibrocartillage?

Answer 8

Found in joint capsules, ligaments, tendon insertions & intervertebral discs (places that need to resist high mechanical forces)
dense bundles of collagen fibres
Strongest type of cartilage

Question 9

Nutrition of cartilage?

Answer 9

Usually described as avascular – not completely true  cartilage channels = pores from blood vessels into cartilage matrix
But most cells distant from vascular supply, so use diffusion from surface (perichondrial) vessels -vessels that supply surface of cartillage
Articular cartilage obtains nutrients via synovial fluid
Cartilage therefore limited to a few mm thickness

Question 10

How does cartillage change with age?

Answer 10

The collagen fibres are affected and composition of cartillage changes

Therefore

Water content of cartilage decreases
Reduced shock absorption
Less protection of articular surfaces & increased risk of damage