Exam #2: Bone

Question 1

What does pressure being applied to bone result in?

Answer 1

Bone resorption (breakdown)

Question 2

What does tension being applied to bone result in?

Answer 2

Bone deposition (addition)

Question 3

What percentage of Ca++ is stored in bone?

Answer 3

99%

Question 4

Metaphysis

Answer 4

Angulation between the diaphysis & epiphysis

Question 5

What is the difference between active/growing periosteum & inactive/ mature periosteum?

Answer 5

• Active (growing)= 2x distinct layers

- Inactive= mostly outer fibrous layer with a poorly defined inner layer

Question 6

Characteristics of the Outer Fibrous Layer of Periosteum

Answer 6

• Dense collagenous CT
• Contains blood & lymphatic vessels, & nerves
• Anchored to bone via Sharpey’s Fibers

Question 7

Sharpey’s Fibers

Answer 7

Bundles of collagenous fibers that anchor the outer fibrous periosteum to the bone

Question 8

Characteristics of Inner Fibrous Layer of Periosteum

Answer 8

• Active= osteoprogenitor cells

- Inactive= periosteal cells

Question 9

Characteristics of Endosteum

Answer 9

• Single row of osteoprogenitor cells
• Lines bone marrow cavity
• Lines Haversian & Volkman Canals
• Covers bony spicules & trabeculae of spongy bone

Question 10

Inorganic Component of Bone Matrix

Answer 10

• Minerals that give bone its hardness

- 65% of the dry weight of bone

Question 11

Organic Component of Bone Matrix

Answer 11

Consists of fibers & ground substance

Question 12

Fibers

Answer 12

• Type I Collagen (acidophilic)

- Prevent bone from becoming brittle

Question 13

Ground substance

Answer 13

• Proteoglycans w/ GAG side chains
• Multiadhesive Glycoproteins
• Bone specific proteins
• Growth Factors

Question 14

Ground Substance Proteoglycans

Answer 14

• Hyaluronan
• Chondroitin Sulfate
• Keratin Sulfate

Function: Bind growth factors

Question 15

Ground Substance Multiadhesive Glycoproteins

Answer 15

• Osteonectin

- Sialoproteins

Question 16

Osteonectin

Answer 16

“glue” between collagen & hydroxyappetite crystals

Question 17

Sialoproteins

Answer 17

• Osteopontin= binds cells to bone matrix

- Sialoproteins I & II= helps bind cells to bone matrix & begins calcium phosphate formation during mineralization

Question 18

Bone -specific, Vitamin K-dependent proteins

Answer 18

Osteocalcin= traps Ca++ from the blood & stimulates osteoclasts to remodel bone

Question 19

BMP

Answer 19

Bone Morphogenic Protein

• induce mesenchymal cells to differentiate into osteoblasts
• Used following surgery to stimulate bone formation

Question 20

What are osteoprogentior cells in the inner layer of periosteum called?

Answer 20

Periosteal cells

Question 21

What are osteoprogenitor cells in the endosteum called?

Answer 21

Endosteal cells

Question 22

Osteoblast Characteristics

Answer 22

• Cuboidal Shaped
• Basophilic due to rER
• Synthesize organic component of bone matrix called osteoid
• Membranes contain a high level of alkaline phosphatase enzyme

Question 23

Osteoid

Answer 23

• Organic component of bone matrix
• Non-mineralized
• Type I Collagen
• BMPs

Question 24

When bone is being synthesized, what increases in the blood?

Answer 24

Alkaline phosphatase levels

Question 25

Alkaline phosphatase enzyme

Answer 25

Mineralizes bone

Question 26

How do osteoblasts communicate with other osteoblasts & osteocytes?

Answer 26

Gap junctions

Question 27

Periosteocytic Space

Answer 27

Space between the osteocyte cell membrane & the lacuna & canaliculi

Question 28

What surrounds an osteocyte?

Answer 28

1) Fluid in the periosteocytic space 2) Osteoid 3) Mineralized bone

Question 29

Characteristics of osteoclasts

Answer 29

- Multinucleated - Motile - Acidophilic - Very large

Question 30

What are osteoclasts derived from?

Answer 30

Monocytes (mononuclear hemopoietic progenitor cells)

Question 31

Ruffled Border

Answer 31

- Site of exocytosis of hydrolyitc enzymes | - Also the site of endocytosis of broken down bone & other products

Question 32

Clear Zone

Answer 32

- NO organelles, but has actin ring | - Sealing zone that isolates the acidic, corrosive resorption compartment

Question 33

Basolateral Region

Answer 33

- Contains organelles | - Functions in exocytosis of broken-down matrix

Question 34

What breaks down the inorganic component of bone?

Answer 34

Acidic environment created by the osteoclasts (H+)

Question 35

What breaks down the organic component of bone?

Answer 35

Lysosomal hydrolases & metalloproteinases

Question 36

How do drugs that slow bone breakdown in osteoporosis work?

Answer 36

Accelerate osteoclast apoptosis

Question 37

Compact Bone

Answer 37

- Dense solid bone that forms a shell around the exterior of long bones - Contains Haversian systems (Osteons)

Question 38

Cancellous Bone

Answer 38

- Spongy bone that lines the marrow cavity of long bones | - Contains an irregular arrangement of lamellae

Question 39

Primary (Immature, Woven, Bundle) Bone

Answer 39

- Forms during fetal development & bone repair - Temporary tissue that is resorbed by osteoclasts and then replaced by secondary bone - Bone lining the alveolar sockets remains immature throughout life

Question 40

Secondary Bone

Answer 40

- Contains parallel or concentric lamellae - Collagen fibers are parallel within lamella - Higher mineral content (stronger) - May exist as spongy or compact bone

Question 41

Haversian Canal

Answer 41

- Vascular space enclosing a neurovascular bundle | - Does NOT contain lymphatic vessels

Question 42

What is the only bone tissue that contains lymphatic vessels?

Answer 42

Perichondrium

Question 43

Rickets

Answer 43

- Ca++ Deficiency or Vitamin D deficiency in which bone does not mineralize properly, leading to bowing of the lower legs in infants - Osteomalacia in adults