Lecture 8

Question 1

list the 3 major classes of cartilage:

Answer 1

Hyaline
Elastic
Fibrocartilage

Differ based on their matrix

Question 2

Functions of cartilage:

Answer 2

Compressible 
Resists distortion
Absorbs shock in joints
Reduces friction in movable joints. 
Necessary for endochondral bone growth.
Involved in fracture repair.

Question 3

What is it called if cartilage persists to the adult form?`

Answer 3

Neotony

Question 4

Cartilage is found:

Answer 4

Part or all of the skeletal system

Question 5

Cartilage FORMING cells

Answer 5

Chondroblasts

Question 6

Cartilage MAINTENENCE cells

Answer 6

Chondrocytes

Question 7

What is the extracellular matrix composed of:

Answer 7

Collagen fibers:
[type II collagen]-[type I in fibrocartilage]

Ground substance:
hyaluronan, chondroitin, keratin, glycosaminoglycans

Question 8

Outer fibrous layer surrounding a mass of cartilage

Answer 8

Perichondrium

Question 9

Chondrocytes are involved in:

Answer 9

Production of the collagen and proteoglycans in the matrix.

Question 10

cartilage is vascular or avascular?

Answer 10

AVASCULAR

Question 11

Chondroblasts

Answer 11

Lay down cartilage maTRIX AND BECOMES CHONDROCYTES

Question 12

Chondrocytes

Answer 12

Maintain cartilage matrix

Question 13

Lacunae

Answer 13

Pockets w/in matrix where the Chondroblasts and Chondrocytes are found

Question 14

Hyaline cartilage characters:

Answer 14

• MOST COMMON type of cartilage
• avascular
• type II collagen
• surrounded by perichondrium
• translucent, bluish gray white
• solid but flexible
• Chondrocytes are often found in cell groups [d/t cell division]
• Growth patterns: Appositional And Interstitial
• mostly a support cartilage
• asso. W/ highly movable joints

Question 15

Appositional growth

Answer 15

Growth that occurs by adding more material to the outside of existing material

Question 16

Interstitial growth

Answer 16

Occurs by inserting additional material into existing substance—-only living tissue can do this

Question 17

Articulate cartilage covered w/ perichondrium?

Answer 17

No perichondrium

Question 18

Cartilage is avascular; is bone?

Answer 18

Nope, bone develops in regions of high O2 [ ]

Question 19

Hyaline cartilage location:

Answer 19

Mammals:
-External auditory meatus 
-Ears,nose
-MovablE joint surface
-Larynx
-tracheal, bronchial cartilage
-fetal long bone
-articulate ends
OTher vertebrates:
-skeletal systems...

Question 20

Fibrocartilage characters:

Answer 20

• Increased collagen in matrix
• Reduced cellularity compared to hyaline cartilage
• not surrounded by perichondrium
• opaque appearance from fibrous texture
• Type I collagen
• single sparse Chondrocytes

Question 21

2 components of bone matrix:

Answer 21

Organic:osteoid- provides flexibility

Inorganic: hydroxyapatite 35-65% of the matrix

Question 22

3 major types of bone:

Answer 22

Woven bone: occurs during bone development and repair.

Compact bone: lamellar bone

Spongy bone: trabecular or cancellous bone

Question 23

General histology of compact bone.

Answer 23

Lacks cavities and forms dense plate on outside of long/flat bones.
Consists of concentric [haversian] lamellae which encircle a central blood vessel and nerves forming an osteon or haversian system.
Osteocytes found btw lamellae located in lacunae and are connected to each other and the Haversian canal via caniliculi
Volkmann’s canal run perpendicular to Haversian canals and connect the Haversian canals to each other and to the surface of the bone

Question 24

Membrane Bone formation:

Answer 24

• bone is laid down in fibrous [collagen] CT matrix.
• osteoblasts use the collagen fibers as a framework to deposit bone matrix
• bone formed w/in the original mesenchyme has a spongy texture: spongy bone
• periosteum may form on either side of the spongy bone.
• periosteum will lay down layers of compact bone on top of the spongy bone (appositional growth)
• generally found in bones that form walls of cavities -cranial vault
• do not form complex articulations
• grow in appositional both diameter and thickness

Question 25

Endochondral bone formation:

Answer 25

1-primary ossification center in future diaphysis of cartilage model.
2-Chondrocytes become hypertrophic
3-Chondrocytes secrete vascular endothelial growth factor
4-Blood vessels break through perichondrium bringing in osteoprgenitor cells
5-Hypertrophic cartilage cells undergo apoptosis, leaving behind thin strands of calcified matrix.
6-osteoclasts use calcified strands as substrates for deposition of osteoid.
7-osteoid is calcified.

Question 26

Advantages of endochondral bone growth:

Answer 26

The bone can grow tall/wide and also repair.