Chapter 6

Question 1

1. Describe the basic characteristics of cartilage

Answer 1

a. Chondroblasts produce cartilage and become chondrocytes chondrocytes are located in lacunae surrounded by matrix
b. The matrix of cartilage contains collagen fibers (for strength) and proteoglycans
c. The perichondrium surrounds cartilage
i. The outer layer contains fibroblasts
ii. The inner layer contains chondroblasts
d. Cartilage grows by both appositional and interstitial growth

Question 2

2. Identify, describe, and give examples of the 3 basic cartilage types

Answer 2

Hyaline
Fibrocartilage
Elastic

Question 3

a. Hyaline Cartilage

Answer 3

i. is a type of cartilage found on many joint surfaces. It is pearly bluish in color with firm consistency and has a considerable amount of collagen. It contains no nerves or blood vessels, and its structure is relatively simple.

a.

ii. Description
iii. Examples
1. Articular cartilage
a. Covers the ends of bones where they come together to form joints

Question 4

b. Fibrocartilage

Answer 4

White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter.Fibrocartilage is found in the pubic symphysis, the annulus fibrosus of intervertebral discs, menisci, and the TMJ. During labor, relaxin loosens the pubic symphysis to aid in delivery, but this can lead to later joint problems

Question 5

c. Elastic Cartilage

Answer 5

a type of cartilage present in the outer ear, Eustachian tube and epiglottis. It contains elastic fiber networks and collagen fibers.[1] The principal protein is elastin.
Elastic cartilage is histologically similar to hyaline cartilage but contains many yellow elastic fibers lying in a solid matrix. These fibers form bundles that appear dark under a microscope. These fibers give elastic cartilage great flexibility so that it is able to withstand repeated bending. The chondrocytes lie between the fibres. It is found in the epiglottis (part of the larynx) and the pinnae (the external ear flaps of many mammals including humans). Elastin fibers stain dark purple/black with Verhoeff stain.

Question 6

3. Describe the composition of bone

Answer 6

a. Collagen provides flexible strength

b. Hydroxyapatite provides compressional strength

Question 7

4. Differentiate among osteoblast, osteocyte, and osteoclast

Answer 7

a. Osteoblast
i. Bone forming cells
ii. Originate from osteochondral progenitor cells
b. Osteocyte
i. Maintains bone
ii. Once the osteoblast is completely surrounded by bone matrix
iii. Lacunae
1. Spaces occupied by the osteocyte
iv. Canaliculi
1. Canals that connect the cells
c. Osteoclast
i. Bone destroying cells
ii. Reabsorb Ca+ and phosphate
iii. Massive Multinucleated
iv. Orivinate from monocyte/macrophage lineage stem cells in red bone marrow
d. Ossification, the formation of bone occurs through appositional growth

Question 8

a. Osteoblast

Answer 8

i. Bone forming cells

ii. Originate from osteochondral progenitor cells

Question 9

b. Osteocyte

Answer 9

i. Maintains bone
ii. Once the osteoblast is completely surrounded by bone matrix
iii. Lacunae
1. Spaces occupied by the osteocyte
iv. Canaliculi
1. Canals that connect the cells

Question 10

c. Osteoclast

Answer 10

i. Bone destroying cells
ii. Reabsorb Ca+ and phosphate
iii. Massive Multinucleated
iv. Orivinate from monocyte/macrophage lineage stem cells in red bone marrow

Question 11

5. Differentiate between compact and cancellous bone

Answer 11

a. Compact
i. Very dense
ii. Central canals
1. Vessels that run parallel to the long axis of the bone
iii. Concentric lamellae
1. Circular layers of bone matrix that surround a common center – the central canal
iv. Osteon
1. Single central canal, its contents, and the associated concentric lamellae and osteocytes
b. Cancellous – Spongy
i. Consists of interconnecting rods or plates of bone called trabeculae
ii. Spaces filled with bone marrow and blood vessels

Question 12

6. Describe an osteon

Answer 12

a. Single central canal, its contents, and the associated concentric lamellae and osteocytes

Question 13

7. Using the example of a typical long bone, differentiate between epiphysis and diaphysis, between periosteum and endosteum, between epiphyseal growth plate and epiphyseal line, between red and yellow marrow

Answer 13

a. Epiphysis and Diaphysis
i. Diaphysis
1. Shaft
2. Composed primarily of compact bone
ii. Epiphysis
1. The part of a long bone that develops from a center of ossification
b. Periosteum and Endosteum
i. Periosteum
1. Connective tissue membrane that covers the outer surface of the bone
ii. Endosteum
1. A single later of cells that lines the internal surfaces of all cavities within bones
c. Epiphyseal Line and Epiphyseal Growth Plate
i. Epiphyseal Line
1. Ossified epiphyseal plate found in adults
ii. Epiphyseal Growth Plate
1. Growth Plate
2. Separates the epiphysis from the diaphysis

Question 14

i. Diaphysis

Answer 14

1. Shaft

2. Composed primarily of compact bone

Question 15

ii. Epiphysis

Answer 15

1. The part of a long bone that develops from a center of ossification

Question 16

i. Periosteum

Answer 16

1. Connective tissue membrane that covers the outer surface of the bone

Question 17

ii. Endosteum

Answer 17

1. A single later of cells that lines the internal surfaces of all cavities within bones

Question 18

i. Epiphyseal Line

Answer 18

1. Ossified epiphyseal plate found in adults

Question 19

ii. Epiphyseal Growth Plate

Answer 19

1. Growth Plate

2. Separates the epiphysis from the diaphysis

Question 20

8. Describe the 5 regions of the epiphyseal growth plate

Answer 20

a. Zone of resting cartilage
i. Nearest the epiphysis
ii. Cells are randomly arranged
iii. Do not divide rapidly
b. Zone of proliferation
i. Chondrocytes produce new cartilage through interstitial cartilage growth
ii. Columns form
c. Zone of hypertrophy
i. Chondrocytes produced in the zone of proliferation mature and enlarge
ii. Cells nearest the epiphysis are younger and actively proliferating
iii. Cells nearer the diaphysis are older and undergoing hypertrophy
d. Zone of calcification
i. Very thin and contains hypertrophied chondrocytes and calcified cartilage matrix
e. Zone of ossification
i.

Question 21

What are the 5 regions of the epiphyseal growth plate

Answer 21

a. Zone of resting cartilage
b. Zone of proliferation
c. Zone of hypertrophy
d. Zone of calcification
e. Zone of ossification

Question 22

9. Compare intramembranous ossification

Answer 22

Embryonic mesenchyme forms a collagen membrane containing osteochondral progenitor cells
No stage is comparable
Embryonic mesenchyme forms the periosteum which contains osteoblasts
Osteochondral progenitor cells become osteoblasts at centers of ossification; internally, the osteoblasts form spongy bone; externally the periosteal osteoblasts form compact bone
Intramembranous bone is remodeled and becomes indistinguishable from endochondral bone

Question 23

Endochondral ossification

Answer 23

Embryonic mesenchyme forms a collagen membrane containing osteochondral progenitor cells
No stage is comparable
Embryonic mesenchyme forms the periosteum which contains osteoblasts
Osteochondral progenitor cells become osteoblasts at centers of ossification; internally, the osteoblasts form spongy bone; externally the periosteal osteoblasts form compact bone
Intramembranous bone is remodeled and becomes indistinguishable from endochondral bone

Question 24

a. Intramembranous ossification (simple)

Answer 24

i. Takes place in connective tissue membranes

ii. Initially produce woven bone which is then remodeled

Question 25

b. Endochondral ossification (simple)

Answer 25

i. Takes place in cartilage

ii. Initially produce woven bone which is then remodeled

Question 26

9. Compare intramembranous ossification to endochondral ossification

Answer 26

a. Intramembranous ossification
i. Takes place in connective tissue membranes
ii. Initially produce woven bone which is then remodeled
b. Endochondral ossification
i. Takes place in cartilage
ii. Initially produce woven bone which is then remodeled

Question 27

10. Differentiate between growth in bone length and growth in bone width

Answer 27

a. Length
i. Epiphyseal plate growth involves the interstitial growth of cartilage followed by appositional bone growth on the cartilage
ii. Epiphyseal plate growth results in increased length of the diaphysis and bony processes. Bone growth in length ceases when the epiphyseal plate becomes ossified and forms the epiphyseal line
b. Width
i. Appositional bone growth beneath the periosteum increases the diameter of long bones and the size of other bones
ii. Osteoblasts from the periosteum form ridges with grooves between them. The ridges grow together, converting the grooves into tunnels filled with concentric lamellae to form osteons
iii. Osteoblasts from the periosteum lay down cicumferential lamellae which can be remodeled

Question 28

11. Identify the 6 shapes of bones and provide an example of each

Answer 28

a. Long Bones
i. Most bones of the upper and lower limbs
b. Flat Bones
i. Certain skull bones
ii. Ribs
iii. Breastbones (Sternum)
iv. Shoulder blades (scapulae)
c. Short
i. Carpal
ii. Tarsal
d. Irregular
i. Vertebral
ii. Facial
e. Sutural
i. Grows along the skull suture
f. Sesamoid
i. Grows in a tendon or ligament
ii. Knee cap (patella)

Question 29

b. Flat Bones (examples)

Answer 29

i. Certain skull bones
ii. Ribs
iii. Breastbones (Sternum)
iv. Shoulder blades (scapulae)

Question 30

c. Short (examples)

Answer 30

i. Carpal

ii. Tarsal

Question 31

d. Irregular Bone (examples)

Answer 31

i. Vertebral

ii. Facial

Question 32

e. Sutural (examples)

Answer 32

i. Grows along the skull suture

Question 33

f. Sesamoid (examples)

Answer 33

i. Grows in a tendon or ligament

ii. Knee cap (patella)