Ch. 4-5 Cartilage and Bone

Question 1

Chondroitin sulfates

Answer 1

polysaccharide derivatives that make up the firm gel matrix of cartilage. Form complexes with proteins in ground substance to produce proteoglycans.

Question 2

Chondrocytes

Answer 2

Cartilage cells; the only cells in the cartilage matrix.

Question 3

Lacunae

(lacus ~ lake)

Answer 3

Small chambers occupied by chondrocytes

Question 4

antiogenesis factor

Answer 4

Chemical produced by chondrocytes that prevents formation of blood vessels. Reason that cartilage is AVASCULAR.

Exchange of nutrients and waste must occur through diffusion through matrix.

Question 5

Perichondrium

Answer 5

Layer that separates cartilage from surrounding tissue. Contains two distinct layers:

1. Outer: fibrous dense connective tissue. Provides mechanical support/protection. Attaches to cartilage and other structures.
2. Inner: cellular layer. Cartilage growth and maintenence.

Question 6

What are the two mechanisms of cartilage growth?

Answer 6

1. Interstitial growth
2. Appositional growth

Question 7

Interstitial Growth

Answer 7

Chondrocytes in cartilage matrix undergo cell division; daughter cells produce additional matrix that enlarges the cartilage from within. Does not occur in normal adults.

Question 8

Appositional Growth

Answer 8

New layes of cartilage are added. Gradually increases size by adding to the outer surface. Only occurs in adults after minor damage.

1. Cells of the inner layer of perichondrium undergo repeated cycles of devision.
2. Innermost cells differentiate into immature chondrocytes, which produce cartilage matrix.
3. As they are surrounded by new matrix, differentiate into mature chondrocytes

Question 9

What are the three major types of cartilage?

Answer 9

1. Hyaline cartilage (hyalos, glass)
2. Elastic cartilage
3. Fibrocartilage

Question 10

Hyaline Cartilage

Answer 10

The most common type of cartilage. Matrix contains closely packed collagen fibers. Tough but flexible.

Examples: Connections between ribs & sternum, nasal, respiratory (larynx/trachea/bronchi). And articular cartilage (covers opposing bone surfaces within joints)

Note: Fibers are not in large bundles, so not always detectable in microscopy.

Question 11

Elastic cartilage

Answer 11

Resilient and flexible. Contains numerous elastic fibers

• Auricle, ‘pinna’ - external flap of outer ear
• Auditory tube - passageway to middle ear cavity
• Epiglottis
• Cunfeiform cartilage - small cartilages in the larynx

Question 12

Fibrocartilage

Answer 12

Durable and tough. Has little ground substance, matrix dominated by interwoven collagen fibers.

• Between spinal vertebrae
• Between pubic bones of the pelvis
• Around tendons
• Pads within/around joints - resists compression, absorbs shock, prevents damaging bone-to-bone contact.

Question 13

What are the components of osseous tissue?

Answer 13

1. 2/3 calcium salts (calcium phosphate and carbonate)
2. 1/3 collagen fibers

Question 14

Osteocytes

Answer 14

bone cells

Question 15

How do osteocytes communicate with blood vessels?

Answer 15

slender cytoplasmic extensions that run through canaliculi (passages in the matrix)

Question 16

Where is on the only place where bone is not covered with periosteum? What is it covered with?

Answer 16

joint cavities; hyaline cartilage

Question 17

periosteum

Answer 17

a layer of fibrous (outer) and cellular (inner) layers. Assists with appositional bone growth and attachment of bone to surrounding tissues.

Question 18

What are the six structural distinctions between cartilage and bone?

Answer 18

1. Cells
   * Cartilage:* chondrocytes in lacunae
   * Bone*: osteocytes in lacunae
2. Ground substance
   * Cartilage:* chondrotin sulfate (in proteoglycan) +water
   * Bone:* a small volume of liquid surrounding insoluble crystals of calcium salts
3. Fibers
   * Cartilage:* Collagen, elastic, and reticular fibers
   * Bone:* Collagen fibers predominate
4. Vascularity
   * Cartilage:* None
   * Bone:* Extensive
5. Covering
   * Cartilage:* Perichondrium (two layers)
   * Bone:* Periosteum (two layers)
6. Strenfth
   * Cartilage:* Limited. Bends easily; hard to break
   * Bone:* Strong. Resists distortion; breaking point

Question 19

What are the four metabolic distinctions between bone and cartilage?

Answer 19

1. Oxygen demand
   Cartilage: Low
   Bone: High
2. Nutrient delivery
   Cartilage: Diffusion through matrix
   Bone: Difusion through cytoplasm and fluid in canaliculi
3. Growth
   Cartilage: Interstitial and appositional
   Bone: Appositional only
4. Repair cabilities
   Cartilage: Limited
   Bone: Extensive