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Flashcards in General Bone and joints Deck (25):
1

What cell produces osteoid?

Osteoblasts

2

What does Alk Phos correlate with?

Osteoblast activity

3

What is the role of Osteocytes?

Detect changes in bone stress

4

Mechanism of Bone resorption

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

5

What promotes osteoclastic activity?

IL1, TNF alpha, PTH

6

What inhibits osteoclastic activity?

Calcitonin

7

Organic Matrix composition

- Type 1 collagen
- proteoglycans
- GAGs
- Lipids

-Synth by O-blasts

8

Arrangement of compact bone

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

9

Arrangement of Trabecular bone

- Parellel lamellae
- Mechanical stress

10

Bone Mineral

Hydroxyapatite crystals deposited in collagen fibers

11

What is a cement line

- Proteoglycan rich seams in remodeling or modeling units

12

Modeling Vs Remodeling

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

13

Reversal lines

Scalloped cement lines
-indicates previous resorptive activity

14

Resting cement lines

Smooth lines
-where bone formation temporarily stopped

15

Describe intramembranous ossification

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

-also long bones (width)

16

Zones of growth plate in Endochondral ossification

Resting
Proliferative
Hypertorphic

17

Post mortem Bone exam

-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

18

Post mortem Joint exam

Open several joints **MEDIAL aspect**
--EXCEPT for stifle
-Check synovial fluid

19

Important components of synovial fluid

1. viscosity
2. color
3. volume

20

Growth Arrest lines

-Parallel lines
-involving primary trabeculae
-malnutrition

21

Growth Retardation lattice

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

*Retention of primary trabeculae*


22

Causes for Premature growth plate closure

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

23

According to Wolff's law, compression...

--> bone formation

Tension --> resorption

24

When is Woven bone normal?

= Immature bone, so Young animals
-pathologic in adults

25

What is Periostium's response to injury?

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