Cartilage

Question 1

What is cartilage?

Answer 1

An avascular connective tissue that consists of an extensive extracellular matrix in which lie chondrocytes.

Question 2

What produces and maintains the extracellular matrix in cartilage?

Answer 2

Chondrocytes

Question 3

Why is there a large ratio of glycosaminoglycans to type II collagen in the cartilage matrix?

Answer 3

Permits ready diffusion of substances between the chondrocytes and the blood vessels that surround the cartilage

Question 4

What assists the resilience of cartilage to the repeated application of pressure?

Answer 4

Large amount of hyaluronic acid in the extracellular matrix

Question 5

What does the high density of negative charges on the GAGs do?

Answer 5

Attracts water, forming a hydrated gel

Question 6

What does hyaluronic acid together with its attached proteoglycan monomers form?

Answer 6

A hyaluronate proteoglycan aggregate

Question 7

What are the three types of cartilage?

Answer 7

Hyaline, Elastic and Fibrocartilage

Question 8

What does the matrix of hyaline cartilage consist of?

Answer 8

Proteoglycans, hyaluronic acid and type II collagen

Question 9

What does the matrix of elastic cartilage consist of?

Answer 9

Has a matrix like hyaline cartilage but with the addition of many elastic fibres and elastic lamellae

Question 10

What does the matrix of fibrocartilage consist of?

Answer 10

Has a matrix like hyaline cartilage but with the addition of abundant type I collagen fibres

Question 11

What is the cell type found in hyaline cartilage?

Answer 11

Chondrocytes

Question 12

What are isogenous groups?

Answer 12

Small clusters of recently divided chondrocytes

Question 13

When do the chondrocytes within the isogenous groups seperate?

Answer 13

As they lay down the extracellular matrix

Question 14

In early fetal development, hyaline cartilage is the precursor model of the bones which develop via which type of ossification?

Answer 14

Endochondral ossification

Question 15

As long bones develop, where does some hyaline cartilage remain?

Answer 15

At the articulating surface and also at the epiphyseal plate until growth ceases

Question 16

Where is hyaline cartilage found in the body?

Answer 16

Articulating surfaces, rib cage, trachea, bronchi and larynx

Question 17

What is the perichondrium?

Answer 17

Dense irregular connective tissue that covers the margin of hyaline cartilage

Question 18

What does the perichondrium contain?

Answer 18

Many elongated, fibroblast-like cells which can develop into chondroblasts and thereafter into chondrocytes

Question 19

What is appositional growth of cartilage?

Answer 19

Fibroblasts in the perichondrium give rise to flat, newly formed chondroblasts which secrete matrix components and round up to develop into chondrocytes, resulting in cartilage growth.

The process of appositional growth occurs when the cartilage model also grows in thickness due to the addition of more extracellular matrix on the peripheral cartilage surface, which is accompanied by new chondroblasts that develop from the perichondrium.

Question 20

What is interstitial growth of cartilage?

Answer 20

The cartilage model will grow in length by continuous cell division of chondrocytes, which is accompanied by further secretion of extracellular matrix. The cells of the isogenous groups separate as they lay down further matrix.

Question 21

What is the lacunae in cartilage?

Answer 21

Spaces in which the chondrocytes lie

Question 22

Where is there no perichondrium?

Answer 22

At articulating surfaces

Question 23

What is the epiphyseal growth plate formed from?

Answer 23

Hyaline cartilage

Question 24

Hyaline cartilage calcifies with ageing. What about elastic cartilage?

Answer 24

Elastic cartilage does not calcify

Question 25

Where is elastic cartilage found in the body?

Answer 25

Pinna of the ear, epiglottis, Eustachian tube

Question 26

How do elastin fibres stain?

Answer 26

Dark staining

Question 27

What are the cell types present in fibrocartilage?

Answer 27

Chondrocytes and fibroblasts

Question 28

What is fibrocatilage a combination of?

Answer 28

Dense regular connective tissue and hyaline cartilage

Question 29

Does fibrocartilage have a perichondrium

Answer 29

No

Question 30

Where is fibrocartilage found in the body?

Answer 30

Intervertebral discs, menisci of the knee joint and pubic symphysis

Question 31

What does fibrocartilage act as?

Answer 31

Shock absorber

Question 32

How are chondrocytes often arranged in fibrocartilage?

Answer 32

In rows or as isogenous groups

Question 33

What is an enthesis?

Answer 33

Points of attachment of tendon and bone - fibrocartilage is often present

Question 34

What is endochondral ossification?

Answer 34

Involves the replacement of a pre-existing hyaline cartilage template by bone. This is the way in which most bones develop.

Question 35

What happens to the epiphyseal plate of long bones after the cessation of growth?

Answer 35

Disappears

Question 36

How is the synthetic activity of the chondrocytes directed?

Answer 36

Pressure loads applied to the cartilage create mechanical, electcal and chemical signals that direct the synthetic activity of the chondrocytes

Question 37

At which stage of embryonic development does a collar of periosteal bone appear in the shaft?

Answer 37

6-8 weeks

Question 38

At which stage of development does central cartilage calcify and a nutrient artery penetrate to supply osteogenic cells?

Answer 38

8-12 weeks

Question 39

At 8-12 weeks, central cartilage calcifies and a nutrient artery penetrates to supply osteogenic cells. What is formed?

Answer 39

Primary ossification centre

Question 40

When does the medulla become cancellous bone and cartilage form epiphyseal growth plates?

Answer 40

Post-natal

Question 41

After birth, what to epiphyses develop?

Answer 41

Secondary centres of ossification

Question 42

When do epiphyses ossify and growth plates continue to move apart and lengthen bone?

Answer 42

Pre-pubertal

Question 43

What is the final state of endochondral ossification?

Answer 43

Epiphyseal growth plates replaced by bone but hyaline articular cartilage persists

Question 44

The bone increases in length via which type of ossificaition?

Answer 44

Endochondral ossification

Question 45

The bone increases in girth (periosteal ossification) via which type of ossification?

Answer 45

Intramembranous ossification

Question 46

What is the synovial joint?

Answer 46

A moveable joint in which the opposed bone ends are: - Covered by hyaline cartilage or fibrocartilage - Lie within lubricating synovial fluid bounded by an articular capsule which is lined by a synovial membrane and reinforced with fibrous tissue and ligaments

Question 47

What does the synovial membrane consist of?

Answer 47

Macrophages and fibroblast-like cells which secrete the synovial fluid

Question 48

What is the fibrous capsule continuous with?

Answer 48

The periosteum

Question 49

Which type of connective tissue is the periosteum?

Answer 49

Dense CT

Question 50

What are the 4 zones of an epiphyseal growth plate?

Answer 50

Zone of proliferation - cells actively dividing Zone of hypertrophy - cells enlarge greatly Zone of calcified cartilage - cells begin to degenerate and matrix calcifies Zone of resorption - calcified matrix in direct contact with the marrow cavity