L1 - Cartilage

Question 1

Where is cartilage found?

Answer 1

In articular joints of bones
In organs such as the trachea and bronchi
Costal cartilage connecting ribs to sternum
In the larynx
In the growth plate of long bones
In the nose, ears, epiglottis and Eustachian tubes

Question 2

What are some properties of cartilage?

Answer 2

CT from mesenchymal stem cells 
Tough and resilient 
Contains 60-80% water 
No nerves or blood vessels 
Difficult to repair if damaged

Question 3

Cartilage is covered with what?

Answer 3

Dense perichondrium which helps resist outer cartilage expansion when compressed
Contains stem cells

Question 4

How do nutrients and gases travel through cartilage?

Answer 4

By diffusion

Question 5

What are the main two cell types in cartilage?

Answer 5

Chondroblasts and chondrocytes

Question 6

What are chondroblasts?

Answer 6

Forms initial cartilage (builds) and is located next to the perichondrium
Mitotic
Precursor to chondrocyte

Question 7

What are chondrocytes?

Answer 7

Mature cells within spaces called lacunae
Separated from one another by ECM
Can proliferate to form clusters called isogenous groups

Question 8

What is the amorphous component of cartilage?

Answer 8

ECM containing hyaluronic acid, proteoglycans and water

Question 9

Which fibers are present in cartilage?

Answer 9

All have type II collagen but some have added elastin or type I collagen as well

Question 10

What is perichondrium?

Answer 10

Layer of dense irregular CT covering hyaline and elastic cartilage
Essential for growth and maintenance of cartilage

Question 11

Describe the outer/fibrous layer of perichondrium

Answer 11

Largely type I collagen and fibroblasts

Question 12

Describe the inner/chondrogenic layer of perichondrium

Answer 12

Adjoins cartilage matrix
Contains mesenchymal stem cells serving as a source for new chondroblasts that will divide and differentiate into chondrocytes

Question 13

What is the most abundant type of cartilage?

Answer 13

Hyaline cartilage

Question 14

Describe characteristics of hyaline cartilage

Answer 14

ECM contains type II collagen fibrils, water, HA and proteoglycans (a very hydrated matrix)
Absorbs shock
Plays a key role in bone development and growth
Surrounded by a perichondrium

Question 15

What is the surface appearance of hyaline cartilage?

Answer 15

Glassy, shiny and smooth

Question 16

Where is hyaline cartilage located?

Answer 16

Joint surfaces, costal cartilage, larynx, trachea and bronchi, and nose
In moveable joints it is surrounded by a synovial fluid (glides easily)

Question 17

List characteristics of elastic cartilage

Answer 17

Similar to hyaline but contains an abundant network of elastic fibers embedded in type II collagen
Elastic fibers allow for recoil/rebound —> retains shape after deformation
Flexible
Perichondrium present

Question 18

Where is elastic cartilage located?

Answer 18

Auricle of the ear, walls of external auditory canals, auditory (Eustachian) tubes and epiglottis

Question 19

List characteristics of fibrocartilage

Answer 19

Mix of hyaline cartilage and dense CT
Very tough and resistant to tension yet provides a cushioning support for bone
Chondrocytes arranged in singly in rows of isogenous groups
Sparse matrix of type II collagen with fibroblasts and dense buds of type I collagen

Question 20

Where is fibrocartilage located?

Answer 20

Intervertebral discs, pubic symphysis and select joint capsules

Question 21

Which types of cartilage lack a perichondrium?

Answer 21

Fibrocartilage and articular cartilage

Question 22

List characteristics of articular cartilage

Answer 22

Remnant of original hyaline cartilage template used by the developing bone
Collagen fibers run perpendicular to the tissue surface but bend gradually to form an arc
Establishes 4 layers

Question 23

Where is articular cartilage found?

Answer 23

On surfaces of moveable joints

Question 24

Describe the orientation of fibers in fibrocartilage

Answer 24

Orientated in the direction of functional stress and provides extra tensile strength

Question 25

Describe appositional growth

Answer 25

One layer on top of another

Chondroblasts next to the perichondrium form new cartilage on the surface

Question 26

Describe interstitial growth

Answer 26

Expands within cartilage
Chondrocytes w/in cartilage divide forming clusters of cells called isogenous groups
They then deposit new ECM spreading themselves from one another thereby expanding the cartilage from within

Question 27

What is territorial matrix?

Answer 27

Newly synthesized ECM adjacent to chondrocytes
Stains differently
Seen during interstitial growth

Question 28

Why is cartilage repair slow after damage?

Answer 28

Due to its avascularity and low metabolic rate

Question 29

How is cartilage repaired?

Answer 29

Very slow but more efficient in young children
Cells from the perichondrium invade damaged area and produce new cartilage or dense CT
May even replace it with bone