Cartilage

Question 1

Cartilage is characterized by an extracellular matrix enriched with

Answer 1

1. glycosaminoglycans
2. proteoglycans

(Macromolecules that interact with collagen and elastic fibers.)

Question 2

Cartilage consists of cells called

Answer 2

Chondrocytes

Question 3

Chondrocytes synthesize and secrete the

Answer 3

extracellular matrix

Question 4

Chondrocytes are located in matrix cavities called

Answer 4

lacunae

Question 5

Principal macromolecules present in all
types of cartilage matrix.

Answer 5

1. Collagen
2. Hyaluronic acid
3. Proteoglycans
4. small amountsof several glycoproteins

Question 6

Because collagen and elastin are flexible, the firm gel like consistency of cartilage depends on

Answer 6

electrostatic bonds between collagen fibers and the glycosaminoglycan side chains of matrix proteoglycans.

Question 7

Three forms of cartilage have evolved

Answer 7

1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage

Question 8

In all three forms, cartilage is

Answer 8

avascular

(and is nourished by the diffusion of nutrients from capillaries in adjacent connective tissue
(perichondrium) or from synovial fluid in joint cavities)

Question 9

Chondrocytes exhibit low

Answer 9

metabolic activity

Question 10

The perichondrium is

Answer 10

a sheath of dense connective tissue that surrounds cartilage in most places, forming an interface between the cartilage and the tissue supported by the cartilage.

Question 11

The perichondrium harbors the

Answer 11

vascular supply for the avascular cartilage
and also contains nerves and lymphatic vessels.

Question 12

Cartilage devoid of perichondrium

Answer 12

Articular cartilage

Question 13

Articular cartilage is sustained by

Answer 13

the diffusion of oxygen and nutrients from the synovial fluid.

Question 14

In adult mammals, hyaline cartilage is located in the

Answer 14

1. Articular surfaces of the movable joints
2. In the walls of larger respiratory passages (nose, larynx, trachea, bronchi)
3. In the ventral ends of ribs, where they articulate with the sternum
4. In the epiphyseal plate, where it is responsible for the longitudinal growth of bone

Question 15

Dry weight of hyaline cartilage consists

Answer 15

40% collagen embedded in a firm, hydrated gel of proteoglycans and structural glycoproteins. In

Question 16

Hyaline cartilage contains primarily

Answer 16

Type II collagen

(although small amounts of
collagen types VI and IX are also present.)

Question 17

Cartilage proteoglycans contain

Answer 17

chondroitin 4-sulfate, chondroitin 6- sulfate, and keratan sulfate, covalently linked to core proteins.

Question 18

Proteoglycan aggregates such as……….formed by

Answer 18

** Aggrecan ……**formed by hundreds of proteoglycans are bound noncovalently to long molecules of hyaluronic acid by link proteins

Question 19

% of the wet weight of hyaline cartilage that is
water.

Answer 19

~ 75%

Question 20

Link proteins do ?

Answer 20

Link proteins noncovalently bind
the protein core of proteoglycans to the linear hyaluronic acid molecules

Question 21

An important component of cartilage matrix is the structural multiadhesive glycoprotein called :

Answer 21

Chondronectin.

Question 22

Chondronectin binds specifically to

Answer 22

1. GAGs
2. Collagen type II
3. Integrins mediating the adherence of chondrocytes to the ECM.

Question 23

Cartilage matrix is generally basophilic due to

Answer 23

The high concentration of sulfated GAGs

Question 24

Territorial matrix usually stain differently from the rest of the matrix because

Answer 24

ECM is richer in GAGs and poor in collagen.

Question 25

Territorial matrix is the area

Answer 25

Immediately surrounding each chondrocyte

Question 26

Cartilage cells can give rise to benign tumors called

Answer 26

chondroma's

Question 27

Cartilage cells can give rise to malignant tumors called

Answer 27

chondrosarcoma's

Question 28

Chondrocyte synthesis of sulfated GAGs is stimulated by

Answer 28

Somatotrophin which causes liver to release Insuli like growth factors or somatomedians which stimulate chondrocytes

Question 29

Allmost all hyaline cartilage is covered by a layer of dense connective tissue called

Answer 29

The perichondrium

Question 30

A ll hyaline cartilage is covered by a layer of dense connective tissue **EXCEPT**

Answer 30

The articular cartilage of joints

Question 31

The perichondrium consists largely of

Answer 31

collagen type I fibers and contains numerous fibroblasts.

Question 32

Elastic cartilage is essentially very similar to hyaline cartilage except that it contains an abundant network of

Answer 32

fine elastic fibers in addition to collagen type II fibrils

Question 33

Fresh elastic cartilage has a yellowish color owing to the presence of

Answer 33

elastin in the elastic fibers.

Question 34

Elastic cartilage is found in

Answer 34

1. Auricle of the ear 2. The walls of the external auditory canals 3. The auditory (eustachian) tubes 4. The epiglottis 5. The cuneiform cartilage in the larynx.

Question 35

Fibrocartilage is a tissue intermediate between

Answer 35

dense connective tissue and hyaline cartilage

Question 36

Fibrocartilage is found in

Answer 36

1. intervertebral disks 2. In attachments of certain ligaments 3. In the pubic symphysis 4. Fibrocartilage is always associated with dense connective tissue and the border between these two tissues is not clear-cut, showing a gradual transition.

Question 37

In fibrocartilage the general orientation of the collagen depends on

Answer 37

The stresses on fibrocartilage

Question 38

Intervertebral disks have has two major histological components:

Answer 38

1. Peripheral **annulus fibrosus** rich in bundles of type I collagen 2. Central **nucleus pulposus** with a gel-like matrix rich in hyaluronic acid

Question 39

All cartilage derives from the

Answer 39

embryonic mesenchyme

Question 40

All cartilage derives from the embryonic mesenchyme in the process called

Answer 40

Chondrogenesis

Question 41

The first indication of cell to cartilage differentiation is

Answer 41

the rounding up of the mesenchymal cells which retract their extensions, multiply rapidly, and form cellular condensations.

Question 42

The cells formed by this direct differentiation of mesenchymal cells in cartilage formation are now called

Answer 42

chondroblasts

Question 43

chondroblasts, have a ribosome

Answer 43

ribosome-rich basophilic cytoplasm

Question 44

Further growth of cartilage is attributable to two processes:

Answer 44

1. Interstitial growth, resulting from the mitotic division of preexisting chondrocytes 2. Appositional growth

Question 45

Interstitial growth is the less important of the two processes postnatally. It occurs during the early phases of cartilage formation, when it increases tissue mass by

Answer 45

expanding the cartilage matrix from within

Question 46

Interstitial growth also occurs in the

Answer 46

epiphyseal plates of long bones and within articular cartilage.

Question 47

In the epiphyseal plates, interstitial growth is important in

Answer 47

increasing the length of long bones

Question 48

In articular cartilage, as the cells and matrix near the articulating surface are gradually worn away, the cartilage must be replaced

Answer 48

from within, since there is no perichondrium there to add cells by appositional growth.