Cartilage And Endochondral Ossification

Question 1

What is cartilage?

Answer 1

Avascular tissue that consists of an extensive extracellular matrix in which lie chondrocytes

Question 2

What do the chondrocytes do? (2)

Answer 2

1. Produce and maintain the extracellular matrix

2. Secrete fibrous material such as collagen and elastin which make up cartilage

Question 3

Complete the sentence:

The large ratio of GAGs to type II collagen in the _________ ______ permits ______ __________ of substances between the chondrocytes and blood vessels surrounding the cartilage.

Answer 3

Cartilage matrix

Ready diffusion

Question 4

Despite being solid and firm, how is the extracellular matrix resilient to the repeated application of pressure?

Answer 4

It is pliable

Question 5

Approximately how many GAG units are joined to the core protein in a proteoglycan?

Answer 5

100

Question 6

How does a proteoglycan form a hydrated gel?

Answer 6

The high density of negative charges on the GAGs attracts water

Question 7

What are the three types of cartilage?

Answer 7

Hyaline cartilage-matrix containing proteoglycans, hyaluronic acid and type II collagen
Elastic cartilage-like hyaline but with additional elastic fibres and lamellae
Fibrocartilage-like hyaline but with lots of type I collagen fibres

Question 8

What is the only type of cell found in hyaline cartilage?

Answer 8

Chondrocytes

Question 9

What is the name given to the small clusters of chondrocytes present in hyaline cartilage?

Answer 9

Isogenous groups

Question 10

Complete the sentence:

In foetal development, hyaline cartilage is a _________ model of those bones which develop by ____________ _____________

Answer 10

Precursor

Endochondral ossification

Question 11

What does articulating cartilage reduce?

Answer 11

Friction

Question 12

Where can articulating cartilage be found?

Answer 12

In parts of the rib cage 
Nose 
Trachea
Bronchi 
Larynx

Question 13

What covers the margin of hyaline cartilage and what does it contain?

Answer 13

Perichondrium

Contains many elongate, fibroblast-like cells which can develop into chondroblasts and thereafter into chondrocytes

Question 14

What type of CT is the perichondrium?

Answer 14

Dense CT

Question 15

The growth of the cartilage from the periphery is known as what?

Answer 15

Appositional growth

Question 16

Deposition of further matrix by isogenous groups results in what type of growth?

Answer 16

Interstitial growth

Question 17

True or false: elastic cartilage calcifies with age

Answer 17

FALSE - does not calcify

Question 18

What are the cell types found in fibrocartilage?

Answer 18

Chondrocytes

Fibroblasts

Question 19

What is fibrocartilage a combination of?

Answer 19

Dense regular CT and hyaline cartilage

Question 20

Where is fibrocartilage found?

Answer 20

Intervertebral discs
Articular discs of sternoclavicular and temporomandibular joints
Menisci of knee joint
Pubic symphysis

Question 21

What is endochondral ossification?

Answer 21

Replacement of pre-existing hyaline cartilage template by bone and is the way in which most bones of the body develop

Question 22

What are the stages of long bone development by endochondral ossification?

Answer 22

1. Collar of periosteal bone appears in the shaft
2. Central cartilage calcifies. Nutrient artery penetrates, supplying bone-depositing osteogenic cells. Primary ossification centre has formed
3. Medulla becomes cancellous bone. Cartilage forms epiphyseal growth plates. Epiphyses develop secondary centres of ossification
4. Epiphyses ossify and growth plates continue to move apart, lengthening bone
5. Epiphyseal growth plates replaced by bone. Hyaline articular cartilage persists

Question 23

What is a synovial joint?

Answer 23

Moveable joint in which juxtaposed (opposed) bone ends are:
Covered by hyaline cartilage or fibrocartilage
Lie within lubricating synovial fluid bounded by articular capsule which is lined by synovial membrane and reinforced with fibrous tissue and ligaments

Question 24

What does the synovial membrane consist of?

Answer 24

Macrophages and fibroblast-like cells that thought to secrete synovial fluid