General Bone and joints

Question 1

What cell produces osteoid?

Answer 1

Osteoblasts

Question 2

What does Alk Phos correlate with?

Answer 2

Osteoblast activity

Question 3

What is the role of Osteocytes?

Answer 3

Detect changes in bone stress

Question 4

Mechanism of Bone resorption

Answer 4

PTH binds O-blasts –> retract from bone surface

• -> O-clast attach surface
• -> RANK Lig (O-blast) binds RANK receptor (O-clasts) –> stimulates Carbonic acid & collagenases secretion
• -> acid dissolves mineral / collagenases break down osteoid

Question 5

What promotes osteoclastic activity?

Answer 5

IL1, TNF alpha, PTH

Question 6

What inhibits osteoclastic activity?

Answer 6

Calcitonin

Question 7

Organic Matrix composition

Answer 7

• Type 1 collagen
• proteoglycans
• GAGs
• Lipids

-Synth by O-blasts

Question 8

Arrangement of compact bone

Answer 8

• Concentric lamellae
• Osteons (haversian system)
• Function:
  
  • Reduces propagation of micro cracks = bone strength!

Question 9

Arrangement of Trabecular bone

Answer 9

• Parellel lamellae

- Mechanical stress

Question 10

Bone Mineral

Answer 10

Hydroxyapatite crystals deposited in collagen fibers

Question 11

What is a cement line

Answer 11

• Proteoglycan rich seams in remodeling or modeling units

Question 12

Modeling Vs Remodeling

Answer 12

Modeling

• change shape or contour of bone
• in response to normal growth or dz
• change in external pressures

Remodeling
-Resorption of old bone –> replaced by new bone

Question 13

Reversal lines

Answer 13

Scalloped cement lines

-indicates previous resorptive activity

Question 14

Resting cement lines

Answer 14

Smooth lines

-where bone formation temporarily stopped

Question 15

Describe intramembranous ossification

Answer 15

Mesenchymal cells differentiate to O-blasts
–> flat bone formation

-also long bones (width)

Question 16

Zones of growth plate in Endochondral ossification

Answer 16

Resting
Proliferative
Hypertorphic

Question 17

Post mortem Bone exam

Answer 17

• Use same long bone always
• -Marrow fat stores / hematopoietic activity
• -Cortical bone (thickness)
• -Trabecular bone (amt/distribution)
• -Metaphyseal plates (Thickness-young animals)
• -Articular surfaces
• -Tendons/ligaments
• Compare gross changes w/ rads
• *Autolysis less severe than other tissues

Question 18

Post mortem Joint exam

Answer 18

Open several joints MEDIAL aspect

• -EXCEPT for stifle
• Check synovial fluid

Question 19

Important components of synovial fluid

Answer 19

1. viscosity
2. color
3. volume

Question 20

Growth Arrest lines

Answer 20

• Parallel lines
• involving primary trabeculae
• malnutrition

Question 21

Growth Retardation lattice

Answer 21

• Dense band of vertically oriented trabecular bone near growth plate
• failure of osteoclastic bone resorption

Retention of primary trabeculae


Question 22

Causes for Premature growth plate closure

Answer 22

1. Hypervitaminosis A
2. Mn deficiency
3. inflammation
4. vascular trauma

Question 23

According to Wolff’s law, compression…

Answer 23

–> bone formation

Tension –> resorption

Question 24

When is Woven bone normal?

Answer 24

= Immature bone, so Young animals

-pathologic in adults

Question 25

What is Periostium’s response to injury?

Answer 25

• Formation of woven bone
  - perpendicular to the long axis of the bone
• Cartilage present if oxygen tension is low