Cartilage

Question 1

3 types of cartilage?

Answer 1

Hyaline - smooth, clear
Elastic
Fibrocartilage (fibrous)

Question 2

Matrix

Answer 2

Contains proteoglycan and hyaluronic acid

Question 3

Hyaline cartilage

Answer 3

Contains chondrocytes which sit in lacuna. Matrix contains type 2 collagen.

Chondrocytes lay down extracellular matrix (ground substance + fibres), and they maintain this.

Avascular with extensive extracellular matrix.

Perichondrium covers margin of hyaline cartilage.

Makes up growth plates in bones.

Question 4

Elastic cartilage

Answer 4

Contains chondrocytes. Matrix contains elastic fibres and type 2 collagen.
Tough but flexible tissue.

There is very little repair in ear once adulthood is reached as chondrocytes have died via apoptosis.

Question 5

Fibrous cartilage

Answer 5

Contains chondrocytes and fibroblasts. Matrix contains lots of type 1 collagen and some type 2 collagen.

It is a combo of dense regular connective tissue and hyaline cartilage.

Cells often seen distributed in rows.
No surrounding perichondrium.

Fewer cells, more collagen.

Question 6

Chondrocytes

Answer 6

Cells responsible for cartilage production. Each cell lies in its own lacuna. Contains vesicles of collagen 2 (stains blue).

Question 7

Interstitial growth

Answer 7

Expansion of cartilage by moving cells away from each other, with new matrix secreted - growth from the centre.

Question 8

Proteoglycan structure

Answer 8

100 hyaluronate proteoglycan aggregates per collagen fibril. Makes a very stiff gel-like substance.

Attracts a lot of water -> prevents compression

Question 9

Where is hyaline cartilage found in the body?

Answer 9

Cartilage of joint, in knees, ankles, wrists, elbows etc.
In nose
In external ear
Costal cartilage
Respiratory tube cartilages in neck and thorax.
Trachea - tough to keep trachea open

Question 10

Appositional growth

Answer 10

Growth from the periphery.

Question 11

Osteophytes

Answer 11

Bony spurs
- these are very painful

Question 12

Where is elastic cartilage found in the body?

Answer 12

3 E’s - the pinna of the ear, the Eustachian tube, the epiglottis.

Question 13

Function of hyaline cartilage

Answer 13

Prevents compression.
Slippery and smooth, helps bones to move smoothly past each other.
Flexible but strong enough to help joints hold their shape.

Precursor of long bones in embryos.
Makes up growth plates in bones.

Question 14

Function of elastic cartilage

Answer 14

Flexible.
Stretch and recoil - returns to original shape even after strong force applied.

Question 15

Function of fibrous cartilage

Answer 15

Acts as a shock absorber and resists shearing forces. Resists compression and bears weight, provides tensile strength.

Question 16

Fibroblasts

Answer 16

They secrete collagen proteins and extracellular matrix. They have a flat nucleus.

Question 17

Where is fibrous cartilage found in the body?

Answer 17

Intervertebral discs, joint capsules (synovial joints), temporomandibular joint, sternoclavicular joint, pubic symphysis.

Question 18

Epiphyseal growth plate

Answer 18

Zone of reserve cartilage
Zone of proliferation
Zone of hypertrophy
Zone of calcified cartilage
Zone of resorption

Question 19

Achondroplasia

Answer 19

Chondrocytes not growing.

Fibroblast growth factor (FGF) promotes collagen formation from cartilage. In the disease, protein functions abnormally, slowing down the growth of bone in the cartilage of the growth plate.

This affects endochondral ossification only (intra-membranous ossification unaffected).

-> results in short stature, but normal sized head and torso

Question 20

Osteoarthritis

Answer 20

Age related degeneration. Mechanical failure of articular cartilage which causes narrowing of joint space -> bone rubs against bone as cartilage has been worn away.

Osteophytes form (can be seen on x-ray).

Question 21

Rheumatoid arthritis

Answer 21

Autoimmune disease causing inflammation of the synovial membrane and thickening of joint capsule.
Due to immune system rheumatoid factor.

Leads to damage to underlying bone and articular cartilage, which causes both the bone and cartilage to disintegrate.

(Damage of bone, then epiphysis, then cartilage, then both disintegrate.)

Question 22

Articular cartilage

Answer 22

Aka hyaline cartilage - the smooth cartilage that covers the end of bones where they meet at joints.