Cartilage

Question 1

What is the function of cartilage in general?

Answer 1

Specialized connective tissue Provides resilient support Resists compressive forces Capability to regain shape and size Smooth, cushioned surface for articulating bones

Question 2

What are the cells in cartilage called?

Answer 2

Chondrocytes

Embedded within extensive extracellular matrix (cartilage matrix)

Question 3

What are the three components of cartilage matrix?

Answer 3

1. Fibers
2. Ground substance
3. Noncollagenous multiadhesive glycoproteins

Question 4

What gives mechanical stability to the ground substance?

Answer 4

Fibers

Question 5

What is the primary type of fiber found in the cartilage matrix?

Answer 5

Cartilage-specific collagens

Type II is predominant form

Question 6

Collagen found at the periphery of the chondrocyte and facilitates the link between the chondrocyte and the cartilage matrix

Answer 6

Type VI Collagen

Question 7

Stabilizes type II collagen by facilitating collagen fibril-proteoglycan interaction

Answer 7

Type IX

Question 8

Associated with hypertrophic regions in cartilage where it organizes collagen fibrils into a 3D lattice

Answer 8

Type X

Question 9

Regulates type II collage fibril size

Answer 9

Type XI

Question 10

What is the predominant component of cartilage matrix?

Answer 10

The Ground Substance

Hydrated gel composed of water, ions and proteoglycans

Question 11

What is the predominant proteoglycan monomer?

Answer 11

Aggrecan

Question 12

What are multimolecular proteoglycan aggregates?

Answer 12

Aggrecan monomers bound to a central hyaluronate backbone

Have dense negative charge – keeps the aggregates expanded d/t repulsion, also water and sodium ions are attracted to hydrate the gel matrix

Question 13

Small regulatory and structural proteins that influence interactions between chondrocytes and the ECM

Answer 13

Noncollagenous Multiadhesive Glycoproteins

Question 14

What are some of the noncollagenous proteins?

Answer 14

Chondronectin

Tenascin

Anchorin CII

Question 15

What are the multiadhesive glycoproteins clinically valuable markers for?

Answer 15

Cartilage turnover and degeneration

Question 16

What is the function of chondrocytes?

Answer 16

They produce and secrete the components of cartilage matrix.

Also secrete enzymes that can degrade cartilage matrix.

Maintain the integrity of the cartilage matrix

Question 17

What is the function of chondroclasts? What are they derived from?

Answer 17

Multinucleated cells that degrade calcified cartilage

Derived from monocytes and are similar to osteoclasts

Question 18

What are some hormones that increase synthesis of cartilage?

Answer 18

Growth hormone

Thyroxin

Testosterone

Question 19

What are some hormones that decrease synthesis of cartilage?

Answer 19

Cortisone

Hydrocortisone

Estradiol

Question 20

What are cartilage elements often enclosed in?

Answer 20

A Perichondrium

Question 22

What is the outer part of the perichondrium?

Answer 22

Fibrous connective tissue (primarily type I collagen) secreted by fibroblasts

Contains a capillary plexus, nerves and lymphatics

Question 23

What is the inner part of the perichondrium?

Answer 23

Contains flattened chondrogenic cells that have the potential to become chondroblasts.

Question 24

How are chondrocytes nourised?

Answer 24

Diffusion through the cartilage matrix

Question 25

Do chondrocytes have a high or low metabolic rate?

Answer 25

High – despite being surrounded by an avascaular matrix

Question 26

What are the three main types of cartilage?

Answer 26

Hyaline

Elastic

Fibrocartilage

Question 27

What is the most common type of cartilage? How does it appaear?

Answer 27

Hyaline cartilage

Bluish-white, glassy appearance

Question 28

What surrounds the chondrocyte acting as a biochemical buffer between the cell and the territorial matrix?

Answer 28

Pericellular matrix

Question 29

Is a perichondrium present around hyaline cartilage elements?

Answer 29

Yes

Question 30

What are two types of specialized hyaline cartilage?

Answer 30

Articular cartilage

Epiphyseal plates

Question 31

What is the boundary betwen the deepest zone and three unmineralized zones above it in articular cartilage called?

Answer 31

Tidemark – it is a thick band of mineralized matrix

Question 32

Does articular cartilage have a perichondrium?

Answer 32

No – enables it to remain smooth

Question 34

What is the main component of elastic cartilage?

Answer 34

Elastin – makes it appear yellowish

Question 35

Is a perichondrium present around elastic cartilage?

Answer 35

Yes

Question 36

What does fibrocartilage have a lot of?

Answer 36

Type 1 collagen – makes it appear white and opaque

Question 37

Does fibrocartilage have a perichondrium?

Answer 37

No

Question 38

What is interstitial growth?

Answer 38

Growth from within

Chondrocytes separate as they divide because of new matrix production

Generally occurs in young cartilage

Important in epiphyseal cartilage for growth of long bones

Question 39

What is appositional growth?

Answer 39

Growth from the surface

Inner layer of perichondrium has chondrogenic cells that have the potential to become chondroblasts (express SOX-9)

Chondroblasts secrete cartilage matrix and become enclosed within it.

Adds new cartilage to the surface of existing cartilage

Question 40

What are some changes that occur in cartilage with aging?

Answer 40

Affects matrix organization, matrix mechanical properties and chondrocyte function

Disruption of collagen fibers at surface – rough articular surface

Progressive degeneration can leave deep pits/ulcers

Decrease in proteoglycan content –> cartilage softening (chondromalacia)

Chondrocyte death

Question 41

What types of cartilage injury usually do not heal?

Answer 41

Injury that does not extend across the tidemark d/t lack of influx of chondrogenic cells, fibrin clot or growth factors

Question 43

What types of degenerative changes can affect the intervertebral discs?

Answer 43

Decrease in water content of nucleus pulposis and proteoglycans that do not bind water increases

Size of aggrecan molecules decreases

Increase in collagen causes nucleus to become firm

Tears in annulus fibrosis